Oh gosh certain cliches/tropes are like chocolate covered french fries to me. Every fandom has them or needs them but here's my favorite guilty pleasure list

HP AUs come on, what fandom doesn't have this? And if they don't they need it. I've already seen the graphics on tumblr though I fully believe Steve is a Hufflepuff
Nanny AUs, just the idea of Steve coming in to play Nanny because for reasons Tony's adopted wee!Peter fills me with glee
College AUs, typically I like high school AUs but I think college AUs fit more with the Avengers ages, Young Avengers I'd place in a high school AU, Avengers, totally college.
Friendship fics, not really a trope so much as a genre but I really love fics that focus on the group dynamic of the Avengers as a team but doing silly things when they're not saving the world.
Fairy Tale AUs, I love fairy tales, especially the originals so they're a huge weakness of mine.
Barista AU I actually read this really good fic of Steve owning a coffee house and Tony fell in love with his coffee and then with him. It was adorable.
Werewolf AUs they're fun and fascinating
Pretend Boyfriends trope is always a lot of fun too and I love it when it can be done within canon

I probably have more but these are all I can think of off the top of my head