So upon further research, it was advised to start with Superman: Doomsday in 2007.

Let the #DCAnimatedUniverseChallenge begin https://abs.twimg.com/emoji/v2/... draggable="false" alt="🙌🏼" title="Raising hands (medium light skin tone)" aria-label="Emoji: Raising hands (medium light skin tone)"> https://twitter.com/iAm_Neish/status/1246964855451549696">https://twitter.com/iAm_Neish...

If you’re interested in joining the challenge, this is a pretty good guide to the order of the movies:

https://www.denofgeek.com/tv/a-guide-to-dc-animated-movies/

https://www.denofgeek.com/tv/a-guid... class="Emoji" style="height:16px;" src=" https://abs.twimg.com/emoji/v2/... draggable="false" alt="🗣" title="Speaking head in silhouette" aria-label="Emoji: Speaking head in silhouette">LET’S GOOOOO!!!! https://abs.twimg.com/emoji/v2/... draggable="false" alt="🎥" title="Movie camera" aria-label="Emoji: Movie camera">https://abs.twimg.com/emoji/v2/... draggable="false" alt="🍿" title="Popcorn" aria-label="Emoji: Popcorn">

A Guide to DC Animated Movies | Den of Geek

It's going to be awhile before we get another Justice League movie, but the DC animated movie universe is worth checking out.

https://www.denofgeek.com/tv/a-guide-to-dc-animated-movies/

1. Superman: Doomsday (2007)

7.5/10

https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark">Storyline is interesting and easy to follow
https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark"> Good amount of action/Not boring
https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark"> True to characters

https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark"> Superman annoying (IMO)

Justice League: The New Frontier

5.5/10

https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark"> Good introduction of each character

https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark"> Too many parallel storylines/subplots
https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark"> Failed at integrating them as “The Justice League”
https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark"> If you didn’t know the history of each character, you may have been lost as to who’s who

Batman: Gotham Knight (2008)

6.5/10

https://abs.twimg.com/emoji/v2/... draggable="false" alt="✅" title="White heavy check mark" aria-label="Emoji: White heavy check mark"> Is Batman Dawg!

https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark"> Anime-ish style (not my preference)
https://abs.twimg.com/emoji/v2/... draggable="false" alt="❌" title="Cross mark" aria-label="Emoji: Cross mark"> Took me three tries to actually watch the entire thing - May be hard to follow

https://abs.twimg.com/emoji/v2/... draggable="false" alt="‼️" title="Double exclamation mark" aria-label="Emoji: Double exclamation mark"> More mini stories than one flowing movie