I recently upgraded to the Crow Belts and Ratchet as part of installing a crotch strap in my 6. I have yet to fly with them. I am very impressed with the price, quality, and service.
I went with the 2" belts, same as stock Van's. They actually measure about 1 7/8", but are certified and tested well beyond anything survivable.
Many use 3" belts, which are quite wide and a bit bulky in comparison. Although I have not flown them, I think they will be a bit more comfortable than the 3", at least they are on the ground! (not that that counts.) This might be more personal preference than anything.