I am running Goodyear Marathons now and am happy with them. That being said, I believe Goodyear stopped manufacturing them when they began production of the Endurance line.
RV owners are a funny lot. A number of years ago, Carlisles were considered some of the worst tires you could buy for your RV. Now, I have heard many people speak highly of them. Maxxis tires were considered the standard a few years ago, now not so much. I have run Marathons, Powermax, TowMax and whatever else the dealership or manufacturer has put on a trailer without incident. Keep speeds down, don't overload, maintain recommended pressures, use a tire pressure monitoring system and you can't go wrong.