Just went through this last week. Went to HF and was tempted by the aluminum one but reviews that the corner plastic pieces can melt from the exhaust was concerning. Picked up the steel one, put it all together, very nice and well built and worth the money (on sale all the time. $40 cheapest I saw and that was Black Friday.) However, didn't pay enough mind to the fact that it is too narrow in width (front to back) to carry a trash can. It was hanging off like an elephant on a ball at the circus. Reluctantly returned it.
Splurged on Quadratec Hidden Hitch Cargo Carrier http://www.quadratec.com/products/12033_11_07.htm
It's a beast! Very large, heavy, well-constructed. Added n=6 washers for the main bolts and used blue Threadlocker to keep it all sure. Used it today to haul a ton of trash and recycle up to the road and am happy I got the larger unit. Will be able to haul a good amount of gear and feel good about the integrity of the carrier.
Good luck with your decision.