MOBA's have been changing drastically in the past years, due to the huge interest, but my favorite one remains LoL a lot people would complain calling it a "kiddy game, or one that requires no skill, but that's obviously false. It is dynamic and rewarding, due to the IP system, cause it feels great to buy new heroes with your own effort, though it can be a hassle from time to time. HOTS is also up there for me, because it's really dynamic and the games aren't as long as other MOBA's like Dota 2 for example, that's big plus for me.