I looked at Can Am, Polaris, Honda and Yamaha...did tons of research on different forums on the web. My wife's Ex-husband loaned us his Yamaha Grizzly's and I was very impressed.
We didn't want to buy new, so scoured craigslist for months. For some reason there are a crap ton of Polaris in the area (eastern Nebraska / western Iowa), and not much of anything else. There were a few Can Am's, but most were heavily modified and/or beat to crap. And I didn't want anything bigger than 550.
Found my Polaris Browning LE 550 from a guy just a few miles from my house. 30 hours and less than 300 miles...got good deal. Found the wife a Polaris LE 550 (black with red accents), about 60 miles away, again with 30 hours and ~300 miles. It was mint. Probably paid too much for that ATV, but wife loves it. And now I have matching ATV's...makes maintenance easier.
The Polaris are bigger than the Griz, and seem to ride better. I really like the flip of a switch AWD system. Pulled them to Moab last spring...going back this April.