1994 Polaris ATV
I started grooming with an ATV, but I wouldn't recommend using an ATV. It was always getting stuck, the wheels would dig down to the trail and mix dirt, rocks, and leaves into the snow, and you're exposed to the elements.
If you want to use an ATV, check out the ATV with Tracks. They're expensive, but without them an ATV is not a good option for grooming.