RE: Which ATV???
If you are wanting to stay in themid sizerange, I think my first choice would be a 450 Kodiak. IRS, front locker, on/off 4wd, plenty of power, and Yamaha quality. Second choice would probably be the Honda Foreman or Rubicon.
I own an Arctic Cat 650 but my reasons for choosing it had a lot to do with having room for my wife to ride with me. I love it and it is more than capable of anything I expect it to do. Ride is exceptional andpower is a flick of the thumb away. No other stockATV can match it's ground clearance.
Still, if I was looking for a good all around ATV for just me, I would go with the Kodiak.