In order, best purchase to worst (current or recently manufactured pump guns only):
1) Browning BPS
2) Benelli Nova
3) Remmington 870
4) Ithica 37*
5) Whatever smaller name guns you can find (Charles Daly, for instance)
6) A nicely finished slingshot (the kind with the wrist strap)
7) A poorly finished slingshot (no wrist strap)
8 - (Tie) Whatever cheap Winchester you can find
8 - (Tie) Whatever cheap Mossberg you can find
While I eventually had to find a real job, I was lucky enough to guide duck and turkey hunters from high school through law school, and I still take a few guys each year. I've seen every single shotgun you can buy in action, in the real world, under real conditions. The two things I can say for certain about hardcore waterfowling and turkey guns:
1) a reliable auto is a clean dry auto, hunt in freezing rain, in a duck boat, with mud and dogs and that auto that "hasn't misfired in the 329 years I've owned it" will become a single shot
2) If you can buy it at Wal-Mart, leave it at Wal-Mart. You absolutely positively get what you pay for with cheap guns. Just like the overly favorable review from the auto owner, I can't count the number of times I heard, "This [cheap gun X] has fired 1,239,882 cases of shells, and it's never once hung up". All I can say is, that's not been my experience.
Get a good gun, it's a good investment. It'll last longer than you or I will, and it will be something your kids may be proud to own someday.
* If you're left handed move the 37 up to second