We shoot skeet on a regular basis, and my son shoots competitively. That said, you can't beat a O/U for clays shooting at any level. They just "work". Browning Citori is the best bang for the buck in that category. Immaculate used versions can be had for 1200-1300. There are also many great shooters who use the time-tested Remington 1100. It will shoot 100,000's of rounds with very little attention except for a regular cleaning and a $3 o-ring replaced from time to time. For a do-it-all gun for everything from skeet to ducks, the Beretta autoloaders are hard to beat. That being said, with the ammunition that is available today you can kill a ton of ducks with 2.75" shells. And if that suits you, the 1100 comes to mind again. A good used 11/87 is also a great alternative and will shoot both 2.75" and 3" shells.
Just stay away from Franchi, Stoeger, CZ, and Yildiz if you want a quality gun that will last a lifetime. These ain't one of them. Yeah ...... I'll get a bunch of protests over that statement, but I challenge anyone to run 10,000 rounds through one of them and tell me it was trouble free. And I know there are owners who swear by them. But there are far more who swear at them. I refuse to go into the field with a gun that is questionable or has a proven failure rate.
In the firearms world the statement "You get what you pay for" rings extremely true. Cry once ... not twice.