Mossberg 20
You will get plenty of opinions, both negative and positive about this gun. The earlier ones did have problems, and there is a general snobbery against them (and all Turkish shotguns) in the shotgun community. Most of the comments will come from people who never shot one, or who never owned one.
That said, I have had one for 3 years now and it has functioned flawlessly. It shoots to point of aim, feels good in the hand, and didn't cost a fortune.
Keep in mind that it is a field gun, so if you intend to use it as a sporting gun (as I do) some mods are necessary (which I made). These weren't too expensive and I now have a dedicated 20 gauge skeet gun which has stood up well to the rigors of skeet (far more shots/outing than a day of bird hunting).
If you intend to use this as a sporting gun, PM me and I'll show you what mods I did on mine.