Mauer would've been better choice
The reality of baseball is that a great offensive player at an up-the-middle position is substantially more valuable than a slightly better hitter at a corner position. And when that up-the-middle player is one of the best fielders at his position in baseball, there's absolutely no comparison. Joe Mauer was more valuable than Justin Morneau this past season.
Mauer had a 54-point edge in OBP over Morneau, which overwhelms the advantage Morneau had in slugging percentage, and he is arguably the best-fielding catcher in the game when you consider all aspects of catching. Catchers who field and hit the way Mauer does are extremely valuable, just as shortstops who hit like Derek Jeter does and play passable defense are extremely valuable. First basemen who hit like Morneau just shouldn't win MVP awards in years when there are Mauers and Jeters and other candidates to choose from.