The NFL Around the League "Top 10 Quarterbacks under 25" series came to a close today, and the anticipated number one was indeed Andrew Luck. Greg Rosenthal cited Luck's "wow" plays as the reason for his number one ranking, giving him a slightly higher ceiling than the other players on the list.
You can make a strong argument that any of the quarterbacks in the top five of this list will be a future legend of the game. Luck is my favorite choice because he's already displayed the attributes you want. It's easy to imagine how those skills will translate once Luck refines his game. I expect that rapid improvement to hit this season.