I inherited my grandfather's generic trailer. If it ever had a brand name, it's worn off. Just chiming to say that an open trailer is easier to load and is best for hauling debris, mowers, and things like that. If you want to go the enclosed route, that's okay too. When choosing the size, just make sure you account for the rider needing to get off and exit if you're planning to haul a riding mower, motorcycle, ATV, or anything of that sort.
I personally like both, enclosed and open. We have one of both right now. We have hauled our motorcycles long distance with the enclosed trailer. We bought our open one at the local tractor supply store.