I like the Remington Spartan 453. Don't own one, but I've heavily researched it and sounds like a fantastic gun for multiple uses, 2 3/4" to 3 1/2" compatible. I'd wanna swing it and put it to the shoulder before making a decision, though. The 1100 ain't a bad gun. The Winchester SX is a great gun.
Me, I have a Winchester 1400 that shoots 2 3/4" that is fantastic, reliable, fits me great right out of the box. But, it's no longer made. I've been thinking of getting a auto strictly for waterfowling and looking at the Mossberg 935. However, the 935 chambers 3" or 3.5" only. I do believe they have a model that shoots 2 3/4 and 3", though. I've heard good things about it and it has a tang safety which I like since I'm a south paw shooter.
If you find a Winchester 1400 used at a gun show or something, you could get it REAL affordably and I can tell you that one is a good gun. I've had mine about 20 years and it's fired everything from light dove loads to heavy steel waterfowl loads. It's killed a LOT of winged critters in its 20 years.