This is one of those 'everyone has their own PERFECT answer".... and also would be different in different areas & home designs..
but for us, awning windows were the best type, as you get the whole window ventilation & can keep the windows open in most all rainstorms (we have 3' eaves, so not a great amount of eave protection)
After replacing most all of the aluminum sliders with single awnings, we discovered stacked awning...and wish we had gone that route on all of the windows, much better ventilation control...(see Coastal windows:
http://www.coastalwindows.com/windows/awning )
We have a variety of mfg (Jenweld, Coastal, Pella) due to the time it took to replace all of the windows...all are vinyl, some with standard hardware (not recommend) some with stainless hardware (only type I would recommend)
Aluminum windows do get hit with corrosion if you are near enough to the ocean to get salt (we are 3 miles from & still have salt corrosion) Vinyl is better for us, but fiberglass is most likely the absolute best choice...