Like a few others have said, it comes down to how the gun feels for you. I have a Win SX2 with a 28" barrel, Rem 1100 and 870 with a 26" and have used my dad's 1100 with a 30" barrel quite a bit. I've killed ducks with all of them, but prefer the 28" on a dedicated duck gun. If it were going to serve purposes (ducks, rabbits, upland) as my 870 does I'd go 26" for a bit more versatility.
