Since you are hauling brush and stuff it sounds like the higher sides would be better than the low one. For me I haul shavings for horse bedding and poles/standards/etc for the riding ring so having some side height is helpful (my sides also have steel mesh which I find useful). The side height is irrelevant when I haul my side-by-side or the occasional round bale of hay, and I don't have pallet forks so for me the higher sides are the better choice. I think that is just a matter of evaluating your planned usage.
The biggest advice I will give is to consider tire size. My utility trailer is 6 by 10 with a single 3500 pound axle. I SHOULD be able to put 2800-2900 lbs on it but by the time I am around 1700+ the rinky-dink 13 inch rim, narrow tires that came with it are half flat, even with extra air in them. I would swap them for 15inch tires, but the fenders are too small to allow the extra height or width, so I would have to replace these too, which I can't do without a welder. As well, the bearings seem to wear out faster due to higher impact when those little tires hit potholes and because the high tire pressure makes it bounce around like crazy while it is empty. Take the time to make sure the tires on the trailer are big enough to actually match the axle capacity properly, or that at least there is enough room under the fenders to swap them for bigger/wider tires if you want to.
