Brandon Routh or Christopher Reeve in Man of Steel
How do you think Man of Steel would've been with either Brandon Routh or Christopher Reeve (if he were alive and in his prime today) in the Superman role, if everything else had been the same? How would the portrayal have differed? Would the film have been better or worse? How would it have done at the box office?
And just as another fun speculation, what if Terrance Stamp (in his prime) had been Zod in MOS instead of Michael Shannon?
Anne Hathaway: "You did not just ask me that!! What a forward young man you are!!! My goodness!!"