I'm okay with any type of story. As long as I'm in the fandom.
Here's this list of fandoms I'll read for, Fairy Tail, Teen Titans, Glee, Sonic, and Digimon. (Tamers, and the main cast from 02, Adventure, and Tri. I haven't seen any of the other ones.)
I'm not picky with couples! Throw any couple at me. Even if I don't think they should be together it's like a challenge for you. If you can get me to like them together in the story you know you've written their romance well! I'll ship a couple in a story even if I don't in the main series if the author writes it well.
My favorite couples, and tropes if you're curious: (note, your story doesn't have to have these couples. I'll read any that aren't on my list after this one.)
In general: If your story makes me laugh, or cry I'll remember it.
Okay, I love it when stories are really sad in the beginning and then become really happy. It just makes me so happy to see everything worked out for them.
Robin X Raven
I love reading stories where they're just hanging out at the tower. The team dynamics are adorable.
Sonic the Hedgehog:
Any brotherly fluff between Sonic and Tails.
Tails X Zooey OR Cosmo.
If Sonic tells horrible jokes I am on board.
Exploring the mentality of Shadow.
I really like stories after Dave's breakdown and then he befriends Kurt after he visits him in the hospital. The forgiveness aspect is great, they don't have to date or anything they can be friends.
Any story that explores Sue's character and her softer side.
The friendship between Mercedes and Kurt.
Sam X Quin
Santana X Britney
Exploring TK and Matt's relationship with their parents. It's implied that they're relationships are strained.
TK X Kari
Davis X Ken
Matt X Sora
Matt X Tai (Bonus if there's playful banter.)
Childish banter between Natsu and Lucy.
Gray X Natsu
Gray X Juvia
Sting X Rogue
Rogue X Lucy (They never interact but I've read a few stories for them and they're adorable.)