Factor in the weather where you'll be camping.
We get hail here. A lot of hail. Our first TT ended up totaled because of hail damage. Largely cosmetic, but obvious and thorough.
Our second TT is fiberglass. So far, we've been hailed on three times on camping trips this year. At least a couple of more times when we haven't been camping. None of it was big enough to do damage to the fiberglass or vents/windows/skylights, but it probably would have been just big enough to ding the aluminum siding, requiring another round with the insurance company.
Hail may not be an issue in your area, but it was the deciding factor in our aluminum/fiberglass decision.