Best brand & type of tire for a tow dolly?

Radial should far outlast bias ply.

I think you may find you need "truck" tires, Load Range E or at least D. Reason I say that is the vehicle you're carrying is likely to have much larger tires than what will fit on the dolly. That means you need to squeeze much more capacity into the tire size for the dolly, than a comparable car would carry on that same physical size.
In theory, Dolly is more a Trailer than a Truck, and purists will say "ST" tires for Trailers, "LT" (range D or E) for Truck. Problem is, the vast majority of "ST" tires seem to be imported junk, and there are a number of good choices in "LT."

I put a new set of Gladiator tires on my Demco Kar Kaddy last year at the recommendation of our family owned tire company. They usually have the best value tires on hand for the very large customer base. I am very pleased after our round trip to the keys last year and useage so far this year. 5,000 miles so far and pleased with their performance.

Quality car tires are hard to beat. They run the coolest of any tire. And the treadwear will last the longest. Just make sure the carrying capacity is rated above and beyond the actual weight carried.
If the dolly is of a rigid design like Acme, the tires will not last as long as any steerable wheel dolly.

And I can tell one thing, don't buy any Goodyear ST's trailer tires, there ****.