FrogReaver
The most respectful and polite poster ever
There is no opportunity cost in dpr at level 12. You can have max stat and gwf
Run the numbers again, giving the non GWM fighter +1 to hit and damage (the opportunity cost for the GWM feat).
Also; when you factor in magic weapon damage, it gets even less attractive an option (just like it becomes a less attractive option for rogues with sharpshooter - youd rather land a sneak attack of +10d6 than risk missing with a sneak attack +10d6+10