Shotguns are more about feel that anything. I absolutely love my Nova. Wouldn't trade it for any other pump gun. But is it "better" than a mossberg 835, Rem 870 express super mag, Winchester SXP, or Browning BPS, or Ithaca? No.
As far as Semi's go, go to a LGS or retail store and handle them. See which ones feel right and shoulder well. Mossberg, Remingtons, and Winchesters, CZ, and Escort, can all be had well under a grand. And they are all great performers. Not that other manufacturers don't make good guns, those are just the ones off the top of my head that can be found new under a grand.
As far as tubes go, I shoot Carlson's for waterfowl, and the Primos JellyHead on turkey. They are both great tubes, pattern very well, and are relatively cheap. But every gun has tubes and loads that it prefers. Do you NEED tubes? No. Do they make a difference? In some guns, yes. In others, not a bit.