What follows is a thread vaguely defining as many manga magazines as I can, for reasons. This is not scientific, just a "putting names to faces" thing.

Weekly Shonen Jump
Audience/vibe: intended for teen boys, but hugely popular with girls and older readers, too. The biggest magazine.
Notable titles: One Piece, Dragon Ball, My Hero Academia

Weekly Shonen Magazine
Audience/vibe: teen boys, has been described as "something you'd find in the guys' locker room". Big sports presence as such
Notable titles: Hajime no Ippo, Fairy Tail, Great Teacher Onizuka

Weekly Shonen Sunday
Audience/vibe: teen boys, but the editor-in-chief has an explicit focus on "heroines", seemingly to court a broader audience. Less action, more mystery and slice of life.
Notable titles: Detective Conan (Case Closed), Komi Can't Communicate, Ranma 1/2

CoroCoro Comic
Audience/vibe: you know, for kids! Lots of cross-media material as such.
Notable titles: Doraemon, Super Mario-kun, Pokemon

Weekly Young Jump
Audience/vibe: young adults. Like actual young adults, late teens, early 20s. Vibe changes frequently but you get a lot of violence, a lot of cutesy stuff.
Notable titles: Gantz, Golden Kamuy, Kaguya-sama: Love is War

Weekly Young Magazine
Audience/vibe: young adults, much like Young Jump. Actually pretty quirky, with a lot of unusual titles and sequels/spin-offs to older series from here and Shonen Magazine.
Notable titles: Initial D, Prison School, Akira

Ciao
Audience/vibe: 8-14 year old girls. Vibe is cute and magical.
Notable titles: Hamtaro, Revolutionary Girl Utena, Beauty Pop

Monthly Shonen Magazine
Audience/vibe: similar to Weekly, but I always feel like the monthly versions of magazines skew a LITTLE more mature. This is now a digital magazine, I think?
Notable titles: BECK, Welcome to the Ballroom, Your Lie in April

Bessatsu Shonen Magazine
Audience/Vibe: see previous. This one is in print. The previous one used to be called this, back in the 70s. No, it isn't confusing, thanks Kodansha
Notable titles: Attack on Titan, The Flowers of Evil, O Maidens in Your Savage Season

Jump SQ
Audience/Vibe: Exorcists with swords, samurai with swords, sci-fi teens with swords. Some other stuff with sports and mysteries and such. Also some sequels to other Jump titles.
Notable titles: Blue Exorcist, To Love-Ru Darkness, Twin Star Exorcists

Jump SQ. Rise
Audience/vibe: some magazines have irregular spin-off magazines for certain titles. This one is for fans of the four series they run and no-one else.
Notable (ALL) titles: Blood Blockade Battlefront -Back 2 Back-, Mr. Clice, Beet the Vandel Buster, D. Gray-Man

Weekly Morning
Audience/Vibe: for adult men, with a very heavy vibe of "adult life".
Notable titles: Cooking Papa, Gurazeni, Space Brothers

Grand Jump
Audience/Vibe: Adult businessmen and women, and has career manga, sports manga, and thrillers, as well as hornier stuff. Manga from here tend to get dramas over anime, though there are a few.
Notable titles: Sundome!! Milky Way, Play Ball 2, Sing "Yesterday" For Me

Ribon
Audience/Vibe: just like Ciao, it's for 8-14 year old girls. As such, similar vibe. Such is rival publications sometimes
Notable titles: Chibi Maruko-chan, The Gentlemen's Alliance Cross, Whisper of the Heart

Big Comic Spirits
Audience/Vibe: Adult Men. This one has food, romance, sports and business as regular themes, and has housed some legendary series.
Notable series: Goodnight Punpun, I am a Hero, Uzumaki (and MANY more)

Hana to Yume
Audience/vibe: teen girls, but this magazine has titles read by all-comers, especially on the global stage. Comes out twice a month.
Notable series: Skip Beat!, Fruits Basket, Hana-Kimi, Kamisama Kiss (seriously there's so many)

(More to come)

Lala
Audience/vibe: sister magazine to Hana to Yume, you’ve all probably read a Lala series. Iconic shojo stuff, not necessarily more mature than Hana to Yume, but *different*.
Notable series: Snow White with the Red Hair, Ouran High School Host Club, Vampire Knight

Big Comic Superior
Audience/vibe: a bit less adult than Big Comic Spirits, but still adult. Not entirely dissimilar to Grand Jump in feel, just... darker.
Notable titles: Gigant, Blood on the Tracks, Team Medical Dragon

Young Animal
Audience/vibe: adult men’s magazine that I feel like has a reputation for depravity, but also has a bevy of delightful high-quality series.
Notable series: Nana & Kaoru, Berserk, March Comes in Like a Lion

Bessatsu Margaret
Audience/vibe: shojo for cool people. No like the overriding vibe is cool shojo, you know? Shockingly more popular than Margaret, the magazine it spawned from. Like 100k more readers.
Notable works: Lovely Complex, Kimi ni Todoke, Ao Haru Ride

Margaret:
Audience/vibe: teen girls, but not a lot of teen girls. Used to be bigger, but.... it’s just not anymore. Still, it ran Boys Over Flowers, which is worth a lot!
Notable titles: Boys Over Flowers, Aim for the Ace!, The Rose of Versailles

Split the thread, whoops. Got maybe 10-15 more of these in me, because I only know so many magazines. https://twitter.com/maxythebee/status/1385649165238259716

Afternoon
Audience/vibe: monthly companion to Morning, skews a little more youthful in vibe, but still very much a magazine designed for adult men.
Notable series: (TOO MANY SO UH) Big Windup, Land of the Lustrous, Blade of the Immortal, Wave Listen to Me

Good! Afternoon
Audience/vibe: it’s uh.... more Afternoon. Monthly, still. Seinen, still. A spin-off mag that did well enough to stand next to the original, which is neat. Lot of recent anime adaptations.
Notable series: Drifting Dragons, Hanebado!, Ajin: Demi-human

Evening
Audience/vibe: another one of Kodansha’s “one day” magazines, a twice-monthly one for adult men, and still feels younger than Morning, but older than Afternoon. The sphinx’s riddle gone awry, but it’s fine.
Notable titles: Moyashimon, Inuyashiki, Moteki

Sho-Comi
Audience/Vibe: more teen girl comics, but one where the vibe is irreversibly defined in my mind as “mid-00s viz media”, even when looking at modern output.
Notable titles: Fushigi Yugi, Absolute Boyfriend, So Cute it Hurts!!

Kiss
Audience/vibe: adult women, but (and this might be because the two most stylish artists have worked in this mag) probably like trendy women, because it’s a very cool and forward magazine.
Notable titles: Princess Jellyfish, Perfect World, Ex-Enthusiasts: Motokare Mania

Bessatsu Friend
Audience/vibe: it’s teen girls, but feels like the higher end of teen, also if sho-comi felt like mid-00s Viz this is 100% Tokyopop and Del Rey energy, which is a chaos all its own.
Notable titles: Peach Girl, The Wallflower, Mars, Othello

Flowers
Audience/vibe: adult women. Very varied feel, seems to understand how broad its demographic’s tastes can be in a way a lot of magazines fail to do.
Notable titles: Kaze Hikaru, Kids on the Slope, Polar Bear Café

Gessan (Monthly Shonen Sunday if you're horrendously uncool)
Audience/vibe: it's more Sunday, so similar energy, but a bit more mature in a few ways. Less romance more teasing. Less mystery more condoms. Also baseball.
Notable titles: Dai Dark, Teasing Master Takagi-san, MIX

Feel Young
Audience: adult women who like taboo and twisted tales with controversial content. A bit messy, but when you think of iconic josei titles you think of Feel Young
Notable titles: Helter Skelter, Happy Mania, Bunny Drop

Harta
Audience/vibe: fancy lads who like pretty comics. It means treasure, and to its fans it is one. If sister mag Comic Beam (we'll get to it) is cutting edge, this is if the edge was used to gently caress you.
Notable titles: A Bride's Story, Delicious in Dungeon, Hinamatsuri

Comic Beam
Audience/vibe: can't you read? It's for COMIC FREAKS! Alternative comics that ran the gamut, with influences from all over the comics world. Everything is wildly different to what you've seen before!
Notable titles: Bambi, Desert Punk, Thermae Romae, Little Miss P

Betsucomi
Audience/vibe: was for younger teen girls, but has skewed older & older over time, as well as running series that courted the interest of boys as well. Occasionally problematic titles but you GOTTA love them
Notable titles: Hot Gimmick, BANANA FISH, Black Bird, Basara

Monthly Shonen Sirius
Audience/vibe: 16-21 year old boys, for better or worse. A lot of video game adaptations and Extremely Anime-feeling stuff, if you know what I mean. Still, many gems.
Notable titles: Cells at Work, KoF A New Beginning, Chainsaw Princess, Yozakura Quartet

Monthly Shonen GanGan
Audience/vibe: teen boy comics, with a uh HEALTHY dose of literally Square Enix. In a funny way it’s most memorable for the series that AREN’T based on their games.
Notable titles: Fullmetal Alchemist, Magical Circle Guru Guru, Soul Eater, Kingdom Hearts

Monthly G Fantasy
Audience/vibe: teen boys and fantasy lovers, whether that fantasy is demon butlers, a classic tale with guns, or uh having a relationship.
Notable titles: Black Butler, Saiyuki, Horimiya

Ultra Jump
Audience/vibe: adult male stuff, violence, sci-fi, and fanservice by rep, but that’s been changing a lot over the last few years. A monthly sister publication to Young Jump, so similar territory.
Notable titles: Bastard!!, JoJolion, No Guns Life

Weekly Shonen Champion
Audience/vibe: delinquent teens. Teens who wanna be in gangs, be martial artists, be furries, see a boob. Also Saint Seiya fans who wish they were still teens.
Notable titles: Baki, Beastars, Cutie Honey, Saint Seiya spin-offs

I’m beginning to run out of magazines I know a good amount about/are old enough to have 3+ notable titles for me to mention, so these’ll slow down a bit now, but I’ll try and look into ones people have name-dropped and requested and see if any series from them are familiar to me!

But hey, if you made it this far into the journey well done, I hope you’ve enjoyed this.

Wings
Audience/vibe: Every title I know from here is teen girl comics that don’t feel like teen girl comics. Like the four I’ve picked I did not know were shojo as a kid. BL, yuri, & action abound.
Notable titles: Eerie Queerie, Immortal Rain, Dragon Knights, Tokyo Babylon

Manga Action
Audience/vibe: adult men. The vibe seems clearer in the past when it was publishing absolute legends of action and comedy, but looking at the magazine now it’s hard to say. It’s alien to me.
Notable titles: Lupin the Third, Lone Wolf & Cub, Crayon Shin-chan

Sunday GX (GeneX)
Audience/vibe: imagine a magazine no-one reads at all. GX is slowly but surely becoming this. It just does not sell. Shame, as it’s a perfectly fine place to run chapters of stuff between volume releases
Notable titles: Black Lagoon, Vampeerz, Infinite Stratos

Dengeki Daioh
Audience/vibe: .... Otaku, I guess? Lot of light novel adaptations, a LOT of cute stuff, and a few titles that feel like they’ll get you put on a list. So, otaku.
Notable titles: Azumanga Daioh, A Certain Scientific Railgun, Ichigo Marshmallow, Yotsuba&!

Monthly Asuka
Audience/vibe: teen girls, but ones who are decidedly more... gothic. Lots of pretty boys and pretty men and darkness, and yes that means lots of CLAMP
Notable titles: DNAngel, X (and other CLAMP titles), Trinity Blood

Weekly Manga Goraku
Audience/vibe: older men. Perhaps even OLD men. Lots of very long series and a very storied history, but also a lot of ex-Shonen Jump creators, which is my experience from here.
Notable titles: Ginga titles, Otokujuku titles, Go Nagai titles

Monthly Comic Zenon
Audience/vibe: people who liked Jump in the 80s AND people who like a good variety of mature comics, depending on what series you’re reading
Notable titles: Fist of the Blue Sky Regenesis, Kyo Kara City Hunter, Wakakozake, Arte

Saikyo Jump
Audience/vibe: it’s for kids! Lots of card game and video game magazine stuff, and the comics are half that, and half willy and poo-based spin-offs of Shonen Jump titles.
Notable titles: Koro-sensei Quest, Boruto Saikyo Dash Generations, Chopperman, Dragon Ball SD

Manga Time Kirara
Audience/vibe: people who demand structure in their lives at all times. 4 panel comics, all the way down. 3 panels? Nahhhh. 5? BLASPHEMY!
Notable titles: K-On!, Shoulder-a-Coffin Kuro, Doujin Work

V Jump
Audience/vibe: *shudder* Gamers. A video games magazine that also happens to have manga. Usually WSJ spin-offs or card game/video game titles. Digimon and Dragon Quest have long histories here.
Notable titles: Boruto, Dragon Ball Super, Yu-Gi-Oh Sevens

Captain Tsubasa Magazine
Audience/vibe: Sometimes a manga gets its own magazine, and this one is for the legendary football manga Captain Tsubasa, but titles like Fairy Tail have also performed this feat.
Notable titles: Captain Tsubasa Rising Sun, Captain Tsubasa Memories

That’s 50 magazines! Not planning to do defunct mags, and if I’ve not done X magazine it’s just because I don’t know it well enough to mention it or it’s too new to have notable titles or a vibe yet!
.... jeez, I only wanted to do a couple, thanks for driving me on, folk.