Stay away from American Craftsman and Pella Therma star they are both low end products. Simonton is good but they have different grades, if you watch for sale at Lowes they will run a sale on their Atrium window made by Reliabuilt. The Relibuilt is a stronger window both in glass and vinyl. Lowes will have the sale and if you put them on your charge you also get a 5% discount. Im not sure if you are going to install yourself but they also have installation available.
We had 14 windows replaced by West Shore Windows ... expensive ? yes. quality ? Excellent installation ? Excellent.. 300% improvement from my 22 yr old windows.