Couple of things. I wouldn't do business with a company that dropped 7K (roughly 35%) off of a job. The windows in Quotes 2 and 3 are unfamiliar to me as it appears they are private labeled. If you can get some more information on them, the board can give you more feedback.
The last quote is tricky. The Silverline brand is widely regarded as bunk, however, the 8500 is their best window and not a terrible window. It is better than the Excalibur in my estimation. Your father has done business with the company before and like them.
I would get more information on the other two windows and post that up. As it stands, I am leaning towards quote 4 with the Silverlines......did I just type that?