I love this thread, pops up every six months or so on CBR and its awesome to read.
My favourite hero is Captain America, I love the entire idea of him, someone who fights for good (Hear me out) it may seem cliched but he is honestly my favourite, not to mention he has some of the best stories, creative teams and allies! (Falcon, Agent 13, Bucky! Natasha!) I love Captain A.
Villain:
EDIT:
Upon thinking, I'm going to say that my favourite villain is Ultron.
It must be him, he's awesome.