I've got Boat US, and although I've never had to use it for my boat, I've been on two different boats where it had to be used a total of 3 times in the past few years.
The first time we were close to the Jones Beach fishing pier when the motor blew on the boat I was on, and a male and female from Boat US came to the rescue quickly, and towed us back to the ramp at Wantagh Park where my friends trailer was. Their service was excellent.
The other two times I was on another boat. He was having what he later learned were fuel tank problems and had to be towed twice in a few weeks time by the Lindenhurst area. Just my luck, I was fishing with him both times.
The same guy from Boat US answered the call in each instance. He got there quickly. I think he was hanging out over by Gilgo. He towed us back to the dock both times, and his service was excellent.
After seeing this topic come up in different forums several times over the years, and based on my personal experience, I would have to say that both provide excellent service, and the choice is a toss up. You can't go wrong with either.