Who makes the best replacement windows for energy savings price and quality?

Great question - - there are a ton of alternatives and my recommendation is that you consider more factors than just this when selecting replacement windows.

That being said RbA and Simonton make excellent windows that have a long-lasting reputation within the industry.

There is a complimentary e-book on the subject of replacement windows that I think you should read before making any decisions - http://www.WindowHelpBook.com