I think the best 4-wheeler/atv is the John Deere Gator XUV 620. I worked for the Urban Parks Department all of last Summer spending a great deal of time driving one. They can handle pretty much ANYTHING!
After researching the atvs. I believe the John Deere Gator XUV 620 is the best.The John Deere is able to to go through the rough terrein, and can climbs rocks, hills. This atv can do just about anything you want it to do.