I already have Cap and Iron Man.
Cap was my initial unlock, I got IM through the CW promo code. I now have the day 2 400 shards to spend, and after trying a ton of characters, I'm torn.
Black Panther plays the best/strongest to me at least for 10 levels.
Scarlet Witch seems crazy OP-ed for a 200 shard character.
I really, really like Hawkeye (the Matt Fraction/David Aja run, way more than the movie version); I heard he's a lot of work and not a lot of payoff.
So I can unlock Black Panther for 400, or Hawkeye (Hawkguy) and Scarlet Witch for 200 a piece.
I need help deciding. Tell me things. =)