Car dolly's what to look for?

I have a Roadmaster tow dolly, and am very happy with it. I pull many thousand miles a year with my KIA Sportage attached. It has the swivel pan that the tires set into. I have used three different type of tie downs. The first was the one that came with the dolly, it was totally adjustable. I thought it had to many moving parts. I then went to a total basket style I really liked how easy it was to attach, the problem was it started to show signs of ware to early in its life and the baskets just fit the tires. I am now using one that is a little more to put on but so far seems to do the job.

You should already have a break controller for your other trailers so might as well stick with electric brakes. You will want brakes, good luck.