considerations:
steel, wood or aluminum frames.
Siding material, some will delaminate easier than others.
roof construction - rubber, fiberglass, steel (cargo trailers only), aluminum.
All the above will get you a lot of opinions.
I would look at the all fiberglass "burrito" style trailers if you want less worries. The older ones had issues where the walls would sag and bow out over time and create issues, but Im betting the new ones fixed this with steel frames or something. Aluminum or steel frames for the trailer frame, steel is fine and durable, aluminum is lighter and will not rust.
The biggest thing for durability is keeping rain water out of the roof and walls and storing it in the shade or better, under cover.