We use to use fiberglass, but just too heavy. We have a variety of ladders on board, all aluminum, 8' step, and 16',..20',..32'
Buy good aluminum ladders though, and for the proper weight rating. I think mine are 225 LBS. and they seem plenty strong for me weighing 185 LBS.
We also use the Werner Quick Click stabilizer, and put a washer and a self tapping screw through the rubber end caps to keep them from falling off, especially when they're leaned onto a shingle roof, where they tend to pull off from the shingles grabbing them and pulling them off when you put weight on the ladder.
Jeff