Stronger than vinyl. Pultruded fiberglass frames are 8x stiffer than vinyl, which means slimmer sightlines, larger glass areas, and no sagging on big openings.
Won't warp in PNW weather. Fiberglass expands and contracts at nearly the same rate as glass — no seal stress like vinyl can develop over 20+ years.
Paintable. Unlike vinyl, fiberglass frames can be painted any color you want now or repainted later if your style changes.
30-50 year lifespan. Many manufacturers warranty the frame for 30-50 years. Easily outlasts vinyl in the PNW climate.