Please note: I vote for players who I feel are currently having the best years — not just for stars. I also try to factor the portion of of the previous season that follows the All-Star game in a little.
Catcher
American League: Joe Mauer
National League: Yadier Molina
First Base
American League: Chris Davis
National League: Joey Votto
Second Base
American League: Robinson Cano
National League: Brandon Phillips
Third Base
American League: Miguel Cabrera
National League: David Wright
Shortstop
American League: Jed Lowrie
National League: Troy Tulowitzki
Outfield
American League: Mike Trout, Jose Bautista, Adam Jones
National League: Carlos Gonzalez, Carlos Gomez, Andrew McCutchen
Designated Hitter
American League: Edwin Encarnacion