The silverline is complete garbage. I would NEVER offer my customer that window. Its not only cheaply made and designed, its also very cheap looking and will no doubt detract from your home. Dont do it.
Vywinco is also on the lower end .
The simonton 5500 is a pretty good midgrade window with average performance numbers but definitely better than the other 2.
Higher end vinyl would be okna, soft lite, gorell, and sunrise.

Good feedback from mmarsel. The Simonton is the best of that group IMO, but I'd expand your search.

Another vote for the 5500 of that bunch.

I agree with the above. The Simonton is best, but is somewhat bulky in my opinion, and the ratings are not class leading by a long shot.

Thank you for your feedback. I have expanded my search and am now looking at Slocomb, Ideal and Okna. Again double hung replacement windows. They all look good but I asking your opinions once again.

Okna is one of the top performers on the market. Sold and installed thousands and it is a phenomenal unit. I have not personally used the other two, and don't have much feedback to offer on them.

The top Slocomb is pretty good. Ideal is not.

I agree with the two guys.

If you look at the top end Slocumb, its a solid offering. The Ideal does not compare well to the Okna or the Slocumb.

Let us know your feedback once you have looked at them all.