This one is very difficult for me as I love comics and there are a ton of superheros and villans I love. If I had to pick my favourite one I think I would go with Spawn.
Spawn really isn’t a superhero though but more of an anti-hero. Created by Todd McFarlane. Spawn is an ex-CIA operative once names Al Simmons who gets killed and sent to hell where he makes a deal with an evil being so he can see his wife again.
When I first read the comics I was hooked. The way he loved his wife and would do anything to see her again was amazing even though he was turned into a Hellspawn. The good in him made his internal battles great and the power he finds was incredible. Always fighting between his good and evil sides, which lets face it we all struggle with in one form or another, makes for great story lines. You can love him at one point and hate him the next.
I recommend looking into Spawn if you never have. Also if you get a chance check out the Spawn Animated Series. The way it was done was incredible. There was also a movie made which wasn’t to bad.