I'm not a picky eater, but I'm the most picky with burgers

I do not like tomatoes or onions. Lettuce is fine, but warm wilted lettuce is just mushy and shit.
Warm pickles are also terrible.
Ketchup and mustard are great, but they make cheese taste gross and make the bun soggy.

Spinach leaves can be a good replacement for lettuce, some varieties of lettuce can also hold up to the heat of a burger.

Cheese goes underneath the burger patty, ketchup and mustard go on top.

Buns can avoid getting soggy if you just toast them a bit

American cheese is pretty fine as it melts good.

Blue cheese can be very tasty.

Jalapenos go very well on burgers, good replacement for pickles.

also peanut butter is good but humanity isn't ready for this just yet