Whatever you get, if it's bigger than a 20, budget some $$$ (not many) for a slip-on recoil pad. Single shot shotguns KICK, especially with magnum or slug loads. And hang on tight; any movement during recoil is liable to ding you. (I speak as one with a small silver scar in the thumb/index finger web of my right hand from the opening lever of a Stevens 94 12 guage that I was just in too much of a hurry to take hold of correctly).
If you are hunting in heavy cover, you'll find that most shotguns become single shots--you only get one shot per flushed bird or scampering cottontail. So why not just use a single shot: light, cheap, reliable. Did I mention light? Cheap?
My favorite single is the Savage 220 hammerless; next is the Win 37. Unless you need one NOW, shop around. The older guns are much better finished than guns made now at anything like a comparable price.