The only advantage I've ever seen to a semi-auto gun of any kind is that you can use up more ammo faster.:laughing: When I started on the police department, we had several different brands of pump .12 gauge shotguns; the result of different ones winning the bids in different years. But eventually, the department standardized with nothing but the Remington 870s and I suppose that's what they still have. And as many hog and beef killings as I've seen my dad do with a Remington bolt action .22 rifle, and never more than a single shot . . . it just always seemed to me to the one necessary gun on a farm. Ideally, if I thought I might have to dispatch cows, I'd probably want a 30-30 but it's not necessary.
Bird, (and others),
Please understand, I have absolutely nothing against a Remington 870. I have six of them. One has an 18" police barrel and it's my "house gun." My first shotgun, other than a single shot .410, was a 20 gauge Wingmaster. I still have it. They are GREAT guns.
BUT, the original poster said he wanted just one shotgun and that he wanted to shoot skeet. I shoot skeet. Quite a lot actually. Several thousand shotgun shells per year. I just finished reloading about 500 shells. It's what I do on a rainy day. (when I'm not playing on the computer)

I've shot skeet with an 870 pump. I can do pretty well with it, but I would NOT recommend it for a beginner. A semi is just easier to deal with and a much quicker follow-up shot for the pairs.
Canoetrpr, don't be scared off by the prices quoted by some. A brand new Xtrema can be bought for $1150-1200. I bought mine, barely used, for $600. The Urika can be bought new for under $1000. Go on GunBroker.com and search the semi-auto shotgun section for 391, Xtrema, or Urika.
As I said earlier, I don't shoot 3.5" shells. I bought an Xtrema, with the 3.5" chamber, because that's what I found a deal on. And, it doesn't matter. It will still cycle the 7/8 ounce super light skeet loads without a problem.