This may be a contest for the best alternate casting, but I feel like there are tons of people who do not do contests like this because they are afraid to speak their mind.
NOT TODAY, MOVIEPILOT!
Sorry, got carried away there. Anyway, I believe that the cast for Ultron is just right. You have the veterans like RDJ and Chris Evans, and new faces like Elizabeth Olsen and Aaron Taylor-Johnson. This provides the right mix of old and new to transition into Phase III, in which a lot of the characters will get switched up. But until then, the cast of Marvel's Age of Ultron cast will blow audiences away.
The casts that are put into movies are fun to deliberate, so let's hear your thoughts.