Honestly, I thought Andrew Garfield made for a pretty damn good Spiderman. His voice was especially well suited for the role.

Deadpool and Iron Man were both mentioned already, they're cast pretty bang on atm. While not superheroes, Heath Ledger's Joker was probably my favourite role in any superhero movie I've ever seen, and Michael Caine is a great Alfred.

At this point I can't imagine anyone but Hugh Jackman ever playing Wolverine, even though he's never wowed me with the role. Patrick Stewart played an awesome Professor X as well.