Full metal frame:
Such frame was the most popular in the past, due to its competitive price. But the price issue also makes it less popular now, as the gap between metal and fiberglass material are becoming smaller and smaller each year.
Moreover, because of the bad flexibility feature, the metal frame is more easily broken.

Metal and fiberglass combined frame:
This is the most accepted frame by the market now. The main frame body is still metal, while certain part is revised to fiberglass material.

Basic solution is making the long ribs from metal to fiberglass(more for stick umbrella), as long ribs is the most easily broken part during daily use. And the fiberglass mateiral obviously update the flexibility and quality, as you could check with picture below.

Updated solution is making end ribs and main frame section into fiberglass(more for folding umbrella), this structure prevents umbrella getting broken when turns over during strong windy day.

Full fiberglass frame:
Like its name, the whole frame body is made of fiberglass now. It’s worthy for you to get a super wind-resistance umbrella with certain extra expense. Such umbrella is more for high-end promotion program, or customer from windy area.

Other frames:
The frame could also be made of wood material for classic looking, or of carbon for super light weight. There is no best frame, but the most suitable one for your target.

Coating for metal frame:
The most frequently used frame coating is zinc plating and black electroplating. In the past, zinc plating is more welcomed due to its cheaper price. But now, due to the rising price of zinc and environment control, black electroplating is more accepted.