First off, I'd just like to start by saying there is no possible way any of these actors are going to come off as good as the current actors because Marvel did an absolutely AMAZING job at casting these roles. With that being said, here are my candidates for recasting The Avengers!
Captain America - Armie Hammer
Just his looks scream "AMERICA!!!" He naturally looks like he could step into the role of Cap and kick butt. After seeing the trailer for The Man From U.N.C.L.E., he most definitely shows that he can play an action flick (because The Lone Ranger was definitely not that good.... Like at all...). A classy look that has a charismatic side behind the tough badass exterior, Armie Hammer would fill in great for Chris Evans.
Tony Stark - Leonardo DiCaprio
He's already proven he can play a genious millionaire playboy that throws some pretty amazing looking parties (The Great Gatsby and The Wolf of Wall Street), what's to stop him from becoming a THEE genious Billionaire playboy! I mean, he even looks like him! The only thing stopping him from taking over this role is himself in that he doesn't seem to take roles like this. Regardless, I think he could knock this role out of the park.
Thor - Alex Pettyfer
The looks, the accent, he can even pull of the long blonde hair. Granted he will need to bulk up a bit, but I think if given the chance, he could potentially be an even better Thor than Chris Hemsworth..... Who am I kinding, Chris Hemsworth IS Thor. But if you don't buy that then perhaps......
The Goddess of Thunder! - Katheryn Winnick
With the already badass role of viking shield maiden Lagertha from the TV show Vikings, Winnick could take over the role of the female Thor from Marvels recent change to the longstanding male character. Great Odin's beard she looks EXACTLY LIKE HER! Couple that with the accent and the fighting skills acquired from her previous acting role, she could do it. And you know it.
Bruce Banner - Joseph Gordon-Levitt
I mean, tell me he doesn't look like him. They should still use Lou Ferrigno as the template for the Hulk, but aside from that, JGL has proven to be able to play many different characters and roles, a brilliant yet reserved scientist is easily within his boundaries.
Black Widow - Adrianne Palicki
An already proven action movie actress, Adrianne Palicki might possibly look more like Natasha Romanov than Johansson. Plus she can pull off the seductive manipulative spy role that Johansson has perfected through out all her appearances.
Hawkeye - Luke Evans
As an already proven archer and a dragon size trophy kill under his belt (get it?? From The Hobbit??...oh you did get it.. Ok then...my bad), Luke Evans definitely has the looks and the build. This is one I really do think could do better than the current actor.
VISION - MICHAEL FASSBENDER
I know I know, we haven't even seen Bettany in his role as The Vision (and I know he's gonna dominate that role), but WHAT IF he wasn't available? Fassbender has already played an android in David from Prometheus, he has the British accent coupled with the more robotic sounding voice after he gets his head ripped off in Prometheus, I think he could be a great substitute for Bettany.
Ultron - Liam Neeson
Again we haven't seen the new actor in the role yet but just think, how intimidating wouldn Liam Neesons voice be if it sounded all robotified??
Nick Fury - (younger) Kurt Russell
Fiiiiinnnee, this ones more of a joke but look at him! Definitely old school fury. Just chop the long locks off a little bit and BOOM!