Unfortunately this topic will become like Ford vs Chevy vs Dodge.
I use a Demco KarKaddy SS dolly with steerable wheels and surge brakes. Yes, I paid at the top end but I got what I believe to be one of the better dollys. Its heavy. No way can you prop it up on the garage wall. The tongue and ramps however do fold for convenient storage. It comes with a third wheel for the tongue which makes it easy to move. It has ST205/75R14 tires and after towing a 2008 Toyota Avalon over 15,000 miles the tires show no wear. The steerable wheels allow the dolly to track the motorhome without cutting the corner.
I have read several posts here with some of the lighter weight dollys having wheel alignment problems so severe the tires needed to be replaced after as little as 500 miles. It is fixable by doing some cutting, heating, bending and strengthening the axle however.
Bottom line, you get exactly what you pay for. You can of course go the inexpensive way but by the time you do a lot of modifications you could have bought a quality dolly and had trouble free service.
This is just my experience and I'm sure there are those using different dollys that are completely satisfied.
Demco. Doing our Best to Provide You the Best - KarKaddy SS