There are two outstanding 20 gauge autoloaders in production now, the Beretta 391 and the Browning Gold Hunter. I own the Browning and have shot the Beretta a good bit. Both move as well or better than any two holer on the market and are ~ 6.5 pounds. The Beretta needs a couple cases of field loads to break in, the Gold is ready to go out of the box. Both have outstanding resale values with a slight edge going to the Beretta. The Gold is a little more tolerant of light loads, both shoot field loads up through the 3" stuff like clockwork. Both come with plenty of chokes, 3 for the Gold and 5 for the Beretta. Both shoot pretty flat, about normal as field guns go. The Beretta feels a little more trim and dainty in the hand, the Gold a little fatter in hand. Throw them up on a bird or a target and I honestly cannot tell the difference. Both are fantastic shotguns and will quickly replace everything that you don't need to use steel shot in. They will both run you around $800 or a tad more by the time you get it in the truck, but if ever a shotgun was worth it these two are. There are two shotguns in my safe that I would pay whatever it took to replace if I lost them somehow, and my BGH 20 is one of them.
The Benelli Montefeltro is also worth a look for a hunting gun, and it is nearly a pound lighter than the gold and 391. I have shot one a bit and liked it. It is not very tolerant of light loads at all, but that and the extremely low rib are the only drawbacks that I have seen. Feed it field loads and all is well.