My favorite superhero is probably Spiderman, but for Ben's benefit [;)] my favorite "just" Hero is Batman, who I prefer to anyone else. I like that his battles are as much psychological as physical, and he's got an epic aesthetic/theme. I've read more Spiderman than Batman though, mostly because I got those comics as gifts.
Villian is a much harder choice, but I'd probably settle on Venom, even though he's not always the villain.
I hate Superman (possibly irrationally), mostly for being a posterboy.
I watched a lot of the various Batman cartoons, including those with the Justice League, and just about all the movies. I watched X-Men Evolution pretty closely for a while, and really loved that. The original X-men was a bit before my time. I've seen their live action movies, as well as Spiderman's, both Fantastic Four's, each Hulk movie, both Cap movies and Thor movies, and o'course the Avengers. Also started watching the Arrow TV show, which was pretty cool, but like I said, I'm bad at keeping up with series.
I would have to say my favorite hero of all is Wolverine and always has been. I've never followed comics much, but he is the only hero I've tried following with them. Powers aside, his personal story is really interesting to me, especially with how long and complex his past gets.
Other heroes I really like are Rogue, Nightcrawler and Spiderman and for Villains it is Venom.
I am much more interested in the Marvel heroes than anything DC has. I just find the characters more varied and more interesting than DC. to be honest, I couldn't name many DC heroes besides the main Justice League/ Teen Titans members. I'm pretty interested to hear if others have a preference.