I know this probably belongs in the upland section but I wanted to hear what the pros use.
Here are my preferences: 12 Gauge, 1&1/8 or 1 oz. 8&1/2 magnum shot at 1325 fps. or 7&1/2 for pass shooting and pigeons. Skeet 1 & 2 chokes for waterholes, or IC and Lt. Modified for general use, and Lt. Mod. and Imp. Mod. for pass shooting. #9 shot works great for close in shots but is likely to stay in the bird more frequently. #8s are good for all around and the 7&1/2 if most shots will be 30 or more yards away. Use about the same with a 20 gauge but with one step tighter chokes and #8 shot. Cylinder and skeet wound too many birds with a 20 or smaller gauge. Mostly use over and unders now, Brownings and Berettas.