The windows are Milgard Ultra series which is all fiberglass. We evaluated a few different windows and settled on Milgard because they are a local company (manufactured in Tacoma, WA), their great customer service and lifetime warranty for as long as we own the house. Also other window packages were coming in higher and with 50+ windows, cost was a major consideration.
We went with the flat black exterior, but it would have cost an additional $5,000 to do black on the inside, so we decided we were all right with the white. They are also triple glazing, with 2 panes of Low-E coating on the glass to give us a lower U-value averaging .26. Surprising this only added about $500 to the entire $30,000 window package. Triple glazing also helps with sound control from the busy street....but it adds considerable weight to the window...especially with our larger windows. Luckily during install, the window sashes were removed for easier handling.