My personal favorite is an over/under. With screw in choke tubes, you can easily hunt any flying game and shoot Trap, Skeet, or Sporting Clays. You also have two shots just as fast as you can pull the trigger.
I bought my Browning Citori a little over 20 years ago and I have shot well over 100,000 shells through it and it still shoots great.
Rem 870's are fairly inexpensive, but are reliable guns. About 10 years ago a local sporting goods store had a sale on Rem 870's so I bought one, mainly for upland bird hunting and for shooting steel shot for waterfowl. Extra screw in chokes are about $20 each, and again, with a quick change of chokes you can shoot just about any shotgun sport with an 870. Mine has the black finish on the metal and is in a black plastic stock. I call it my ugly gun. I have run 25 straights at Skeet with it, I just have to remember to pump it for the second shot in doubles.
I'm not a fan of auto loaders. Every year just before bird seasons open, a lot of "once a year" shooters show up at our Skeet range. There is always someone with an auto loader that has a problem with a jam, or stuck shell, or some other problem.