Consider using an aluminum flagpole if you are carrying it in a parade or band. Fiberglass flagpoles are heavier than aluminum and will quickly cause exhaustion if held for long periods of time.
Purchase a fiberglass flagpole if you live in an area prone to lighting strikes since fiberglass does not attract lighting like aluminum flagpoles do.
Purchase an aluminum flag pole in areas that receive high winds, such as mountains or desert plain areas. Metal poles come in a wider range of wind resistance ratings, so you can find one that is appropriate for your area.
Choose fiberglass flagpoles in regions where acid rain occurs since the rain will not damage or corrode the fiberglass like it will aluminum.
Choose fiberglass flagpoles if you want a pole color other that metallic. Aluminum poles can be treated so they appear silver, dark brown, bronze or gold. If you want any other color, go with a fiberglass pole.
Choose an aluminum flag pole if you are trying to keep the purchase cost down since aluminum poles are lighter than fiberglass and cost less to ship.