I dunno'. It's a tough one. I'll outline my choices:
For DC, I think my first choice would be Green Lantern (Hal Jordan). The writing through the Geoff Johns run was fantastic, and it's the only superhero rebirth I actually thought was well-written. Either him or Aquaman. He's the king of 70% of the planet, and he's a bit of an underdog. Again, the Geoff Johns run is well-written. I'm pretty fond of Doctor Fate and Wonder Woman though. Wonder Woman has the advantage of being able to draw from Greek mythology, and she's a strong female character (although I find the outfit annoying most of the time).
For Marvel, possibly Squirrel Girl. The most ridiculous concept for a superhero, but Marvel knows it. Hence why she takes down Doctor Doom, Wolverine, Thanos and Spider-man single-handed. Also, Bucky Barnes as Captain America, since he's a really tortured character with a lot of red on his ledger, and aside from his bionic arm he has no powers. I like Ant-man as well, both Hank Pym and Scott Lang (Scott's daughter Cassie was a great character too, so The Children's Crusade left me feeling a bit sad) and I'm excited to see them both in the same movie: Michael Douglas as Hank, and Paul Rudd as Scott. Set to be awesome.
Gonna' throw Judge Dredd out there as well. He ages in real-time, and then there's that whole 'gaze into the fist of Dredd' thing which is possibly the most awesome line in the history of comic books.
But if you want me to list a superhero you haven't heard of, look up Speedball. This one numptyhead started the whole of Marvel Civil War, spent years having the inside of his suit lined with spikes to atone for past wrongs, and recently appeared in a chilling, brilliantly uncomfortable tie-in with Fear Itself.
As far as villains go, I'm going to call Odin (as he is in the comics) a villain and let you pull your hair out trying to figure out why I said that
"Nothing goes down 'less I'm involved. No nuggets. No onion rings. No nothin'. A cheeseburger gets sold in the park, I want in! You got fat while we starved on the streets...now it's my turn!" -Harley Morenstein