I copied this from Skydawggy on another board.... The 5500 is a completely different extrusion. Not only is it more attractive but the welds are much cleaner than the 5050. The extrusions on the 5500 have greater structural integrity and thus a higher DP rating. In addition, the 5500 has much lower air and water infiltration ratings and uses a 3/4" stainless steel balance as oppose to the 1/2 inch on the 5050. The 5500 also uses 2 strip of fin seal and one strip of compression seal on the top sash and 2 layers of compression seal and on strip of fin seal on the sill. Lastly, as you already know, the stepped sill on the 5500 provides and excellent water barrier. Don't assume some guy working at a wholesale warehouse has any in depth knowledge of a product like a window or door. Many of them have had no factory training at all and only know what they've "heard". You are likely to get better information from an installer. Walk away from the next person who tells you the 5500 and the 5050 are almost the same window. The 5300 is much more similar to the 5050. Basically it's the 5050 with a stepped sill but for a few dollars more than the price of the 5300, you can go with the 5500. Here is a link that might be useful: Vinyl Replacement board

We have also been doing extensive research thanks in large part to this site and some of the insightful posters. We saw all the usual suspects including andersen and pella. We were shown the Okna 600 and liked the window more than andersen believe it or not. We have a total of 10 double hungs with no grids. We are doing a ” basic replacement ” and we were quoted $7600 for all 10 windows including installation ( Okna 600 deluxe ). We actually signed a contract last week and think we were given a competitive price although we didnt base our decision soley on price. We should have our windows installed in late February based on all the supplier issues everyone is facing. We are also having a front door installed by the same company and we chose a fiberglass entry door by HMI Doors based on their recommendation. Its a craftsman style door with no side lites and we are paying $3400 including installation. Needless to say, we are excited and can’t wait for our new windows and door.

Pocket sill on the Ultramaxx is a non-starter for me if that is the comparison. The Ultramaxx also has a huge, bulky frame on it despite is relative lack of performance. No comparison as Millworkman said.

Okna is a much better window than Window World and its superior in every way. Window World is made for the budget minded consumer. FYI- window world do not make their own windows, they are made by MI Windows and some may still be made by Alside both of which are not known for making good / quality windows. Why do homeowners sometimes choose Window World? Because they are cheap and they only care about cost and not quality. Okna on the other hand is known for quality, looks, and having some of the best efficiency numbers in the industry. The Okna 500 is a very good window, however if you could see the Okna 600 “ eco pro”, you would really like it.