RE: which semi auto
A friend got a 1187 super mag SPS -- whatever it is... the deluxe Remington 3.5" semi-auto. It shoots no better than my 870 super, but it weighs about twice as much.
He put a scope on it, but that will be coming off shortly, after last season when he busted his face twice. It's a nice gun if you don't mind the weight. If you do go with that model, and you want to use anything but open sights, I'd highly recommend a red-dot model.
They all shoot about the same, you just need to find the right mix of shell/choke that throws a good pattern out of your particular gun.
Get something that you can buy several chokes for - you'll go through a few before you really find one that patterns to your gun's potential. In that regard, Remington probably offers the widest array of chokes.