Gameloft is a given, but I'll suggest Donut Games as an excellent developer. Their games are always really satisfying, as they all share a common art style and menu system. Plus, they're usually 99c, and you can't beat that.
Oh Snap! And Quizical is my new fav cause they flood the store with trivia apps. Hurray for useless information in overpriced media bundles!
After hating BIA and playing the lite of terminator, i thought i was finished with Gameloft. But, their Modern Combat is actually amazing and I got used to the controls when i never got used to BIA. 1. indie devs 2. Ngmoco 3. Gameloft (there started to win back my money with better games)
Gameloft, and, I know Chillingo is only a publisher, and don't develop games, but all games released under Chillingo are pretty good.
I dont like EA because they dont update their games. The games are good, but get boring without updates.