don't let the bad stories you hear about 12 gauge recoil deter you from getting one. I'm not much bigger than you (5'9" 138 lbs.) and a 12 ga. has never thrown me back, made me stumble, etc. If you get a good one with a good recoil pad, hold it tight to your shoulder, don't put your cheek on the buttstock, and keep a good stance and you won't have to worry about the recoil.
I went with an 8-shot Mossie 500 persuader. I like the safety position and the slide release position; it's good for me since I'm a lefty. Compared to other shotguns, the 500 has a bit longer pull and pump, but it has not bothered me at all. They should also be lighter, which feels nicer to me. I hate the feeling of a heavier gun getting jammed back into you.