Buy a window that is EASY to use. I don't like wood windows because wood swells and contracts, and is a maintenance nightmare. I don't like aluminum because it attracts condensation.
So, for me, it gets down to vinyl. Pick a window that is easy to use, and that doesn't have any fancy easy to break parts.
Imagine using the window with the tip of one finger, all bent over with bad leverage (like over a couch bed or countertop) If it works in these circumstances, go for it.
The glass ratings for energy are kind of a mute issue. They all suck, so go with the middle of the road or better, but don't spend a fortune. Save the extra money for good window coverings.
Warranty is the last issue. Choose a window company that stands behind what it sells. Alpine windows (in my area) warranty 20 years to the original purchaser. Weathervane only warranties for 5.
The most common window problem is they loose their "seal" and you end up with moisture between the two panes of glass. This is the warranty issue.
Have fun with your project, and do your homework!
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