When I was doing my trailer shopping I also noticed that some of the aluminum trailers weighed as much as or more than some of the steel ones. That said, don't veto all of the steel trailers out there just because you think they might be too weighty. Decide on the trailer weight best suited for your truck and work from there, vetoing trailers as you find out their weight.
I wound up getting at trails west 'adventure' model trailer. Not at long-term a value as some of the all aluminum, but the right weight and a price tag I could afford. Maybe by the time it's starting to rust out, I'll have enough in my piggy bank for the all-aluminum models out there.
The big thing with steel is keeping them clean, and when you notice the paint starting to peel, get it sandblasted and repainted. A lot cheaper than a new trailer.
My parents sold a 20 year old stock trailer that had minimal rust because it was under cover every winter, kept clean after every use, and repainted when the rust was getting bad. Re did the floor once and lots of light issues but that's any trailer.