I'm gonna be the different one! I'd go with the 11.5 as it looks closer to a standard width, and won't follow the road, crown, tracks in the road as much as the 12.5. See of you can drive with some one, or drive someone's jeep with 12.5 wide tires and see If you like the way it drives. It took me a but to get use to the wandering feeling of the 12.5!
But thy do look good at 12.5 wide!