I own a Mossberg 500 camo, been using for 20 years. My ultimate pump duck gun would be a Browning BPS. However, there is something to be said for a gas operated auto with those heavy steel loads and for 1000 limit, there are options there. My fave, and I've thought about getting one a lot, would be a new Mossberg 935. A 930 would be fine just for ducks, but I like to shoot geese, but I do have this 10 gauge I've been using I REALLY like on geese because of how well it patterns. Nothing wrong with my 500, so I've resisted the urge to get a 935.
I do like the BPS, though. They fit me out of the box and I shoot lefty so I like the ergos of the tang safety. I also like the smooth action of the BPS/Ithaca design and like the fact that there's no shell elevator in the way for loading, points shared by the 500 at lower cost.
I'm not a real fan of the 870 because of ergos and the expresses are rust magnets in the salt marshes and bays where I hunt. Be okay in a camo finish or painted, but me, I'll take the Mossberg over the 870 if only for the ergos.