First and foremost fit, most shotguns today do come with shims, but they do not make the gun fit universal, try the guns in the gun shop and see what guns fit. The barrel should not be what you are looking at, it should just be the bead.

Last time I checked the Winchester 3.5's are 25fps faster and have a higher payload. My 2 cents, Winchester SX2 and SX3 are good choices, Beretta Extrema II is a good choice and my waterfowl gun of choice. Browning another good choice. Benelli not so much though I have a SBE II as a loaner gun that I bought because it was the rage at the time. On the low end of cost the Mossberg 935. Manditory on any shotgun in my opinion is overbored barrel and lengthened forcing cone, Benelli has not followed this path and many gunsmith make a great living performing this task.