Best tire for long term service is one that fits the trailers axle rating plus around 15-20 percent reserve load capacity. Trailers unlike a truck can have too much tire and of course too little tire.
I see too many new folks with lighter weight trailers with OEM 14" tires think they need a 16" 4080-4400 lb/110 psi load G Sailun because thats what many folks with larger trailers (6k-78k-8k axles) are going too.
The best tires for any trailer (rv and non rv) are a commercial grade ST ot LT all steel ply carcass if your expecting 50k-60k miles and up to 7-10 years of trouble free service.
Next down will be poly carcass LT or ST tires.