I've got an 06 Kodiak 450. It's been a great machine for hunting/fishing and everything in between. They require a little more maintanence then some other ATVs, but if you do things yourself, it's not bad.

The breaks go really fast, but they are some of the best available. I've already had to replace my front pads.
New tires are a must, the stock ones suck.

My buddy has a Grizz 660, and my Kodiak will go everywhere it does. Don't know too much about the Arctic Cats.

I'm happy with my Kodiak, and most guys I've talked to really like theirs as well.

Good luck and let us know what you get.