I like scbwr's post. The majority of full timers seem to like 5ers and Class A MH best. Any decent TT will work if it suits your needs. Larger trailers are best pulled with a 3/4 or one ton PU with a diesel.
I really like 4 season trailers. In the West it can be cold at any time of year in the mountains. There can be snow in any month. Sometimes in order to get to the warm places you have to travel through a cold place.
Storage is really important for full timers. It is best not to have to make beds and fold out stuff every night. Give some thought to a solar system and/or generator so you can enjoy the more remote spots. I would also look closely at counter space, size of the refer, nice pantry, and having an oven. Consider residential mattresses. If you have comfortable furniture, can sleep and eat, and have a place for your stuff it will feel like home.