Probably QB, you don't have to worry about getting hit in training camps or practices
RB would be cool but you really go as far as your OL, if they are not up to par, then you may have a very short career. WRs have a long shelf life but you may not be involved in every play (as in getting the ball, not blocking or route running). OL would be hard as the team's offense is all on your performance. I would like to be a pass-situation DE, you don't need to play every down and you get to blitz mostly.