The Otter Pro sleds are pretty substantial. I bought a pro medium last year for towing behind my atv in snow when a wheeled trailer won't work (with track kit on atv).
The sled is a thick roto molded plastic, with good rugged, molded in hitch attachments. Wouldn't want to pull it by hand, but worked very good behind the atv. Also bought the cover for it to keep the snow thrown up by the tracks from getting in the sled. Mainly used it so far to haul gear in and out of camp, but had in mind hauling firewood too so went with the stronger sled. If you think you're going to end up dragging it over gravel or rocks they make a hyfax runner kit to add to bottom of the sled for protection. The last trip I made with my sled in the spring was during the thaw, by the time I left camp most of the snow was gone so ended up towing sled down a gravel road. The hyfax runners got a few scratches but bottom of sled was unmarked. Runners are replaceable.
Otter also has a lighter weight/duty Sport Sled line, and makes the Beavertail line of sleds.