Like the others have said, Yamaha and Honda are the gold standards. My ATV is a Grizzly 660.

If manueverability is an issue, either get a 2WD or a selectable 4wd. I tested this at the dealership, and the bigger ATV's with selectable 4wd would out-turn the non-selectable 4WD's by 1/2 to 1 full machine width in a 180 degree turn. I didn't believe the salesman when he pointed that out, but after we pulled two machines out in the back lot for a demo, I was proven wrong.

I personally like the automatic transmissions. I have never had any problems getting power to the ground.

I also like liquid-cooled engines. A lot of what I do with my ATV, like spot spraying for example, is moving around very slowly with frequent stops. I've done it with air-cooled machines, but it isn't a fun experience. The engine runs hot and I had to wear some extra leg protection to protect me from the heat. Now I can just feel a little extra warmth, but my legs don't feel like they are going to burn completely up.