Which tow dolly to get

As far as I know, Demco is the only tie rod steerable dolly, and is the best of the best. But not saying others won't work good.
Amco is a rigid frame non steerable dolly,...wheels are going straight ahead all the time, even around the corners, and while they seem to work, I myself wouldn't have one.

IMO, the best of the bunch is the DEMCO Kar Kaddy.
Yes, they are pricey, especially if you go for the top of the line with all the bells and whistles (folding tongue, surge brakes, disc brakes, etc.).

I had the lower priced one, no brakes, no folding tongue, just the basic dolly. Like a fool, I sold it. Sure wish I hadn't done that!

I used to have a Master Tow with surge brake. Never had any issues with it. Had one panic stop with it and the surge brake worked flawlessly. Master Tow has pivoting turntable and platform tilts down to drive car up on. Can be trick when it is raining as ramps get slippery. Never had an issue with front air dam on Chevy Malibu, but you need to check for clearance as you pull on the first time. Did not have provisions for safety chains, but was easy enough to fabricate some. Will admit that I ran the first year and a half without them and no problems. But then I got paranoid. Was a bit of a pain to pin the tilting platform after the car was loaded.

What I know is that there are a few that don't have a deck that swivels, you have to leave the steering wheel unlocked so the front wheels turn, bad idea since the key needs to be on. Surge brakes are good and beyond that most are a variation of the same thing.