like many others said, go with the rem. 870. or whatever fits your fancy, but i use an 870 express and love it. you can get a good shape used one for around 200 bucks. everybody and their mother owns one so its easy to find parts and chokes for. they are possibly the most reliable pump shotguns out there. oh, and mine is ugly as sin so i dont mind draggin it through the woods.
Here is a thought nobody has mentioned yet. synthetic stocks are great because they are not affected by weather and they dont scratch up or chip nearly as bad. HOWEVER... they do not weigh nearly as much so if you will be shooting 3.5 magnum loads it has the possibility to kick your ass. wood stocks will get ugly but be a little heavier and make the recoil for a heavy load more bearable.
OH, another though. this is for your pump vs semi question. semi auto is more work to keep working. more mantainance. more can go wrong. BUT, they can help reduce recoil a little because the pressure from the shell is what operates the action. pump are simple and durable. but they will not absorb any shock and everything will come into your shoulder. the semi auto's, in general, will shoot faster than pumps. that can be good or bad. you may want that extra second to calm down and recover from the previous shot to make another good shot.
if you are going to be in the water lookin for ducks and geese i would say a wood stock pump would be your best bet. if you are going to be walking around in the fields looking for dove and pheasant, i would go with a synthetic stock semi auto. for turkeys, i would go with the wood and pump just because i prefer pumps
Well there are some thoughts for you. Now go buy an 870