i have both a 2010 polaris sportsman 500ho 4x4 atv, and a kubota L4400 4x4 tractor. the atv is a great wagon puller, and is easy to transport. its more of a toy, but can work when it has to. it does spend alot of time pulling my 2500lb+ log splitter, which is does fine, but the rear springs dont like it too much.
my tractor can carry alomost the same as the atv can pull, almost never gets stuck, can drive through 3 feet of snow, and can pull 20x what the atv can. when my wood trailer gets too heavy for the atv, the tractor has no problem pulling them both.
i'd buy a used tractor before i bought an atv.....much more useful for things other than wood stuff