For a shotgun, you want to look for a scope with long eye relief (to keep recoil from your eyebrow), about 4"; and low power, because most shots will be within 100 yards, usually. I have an old Redfield 1-4X on my Mossberg, and keep it on 1X most of the time.
try the Leupold VX-I 1-4x20mm . It is super, reasonably priced and lifetime guaranteed. I also have Leupold VX-2 1-4x scopes on rifles and shotgun, very good. I find I usually keep the scope on 1x (no magnification) for shotgun and DG. Fantastic field of view.
You might consider a red dot sight on a shotgun also, great in low light levels.