Guessing this is obviously a materials only bid. Well, they are two different materials. If you don't need wood, the Simonton will have a longer warranty on it.

Yes it’s a material only bid.

Which of the 2 windows are better?

Two different animals. From my point of view I would take the Andersen 100's. The pricing for the Simonton is too cheap.

The size will play a big part in pricing, what size are these units. The 100 only has one sash that opens if that matters. Have never seen the. Pro finish slider, it is hard to keep tract of all of Simonton’s lines.

Most windows are 36 x 34

The pricing makes sense due to the size. The quality becomes less of an issue with that size of window. I would look at both in person operate them and make the call. I believe that is Simonton’s bottom line so you could look at some if there others.

If you go with Andersen 100 series, make sure you follow installation instructions to a T. All of our 100 series frames have bowed after a year and the rep came out and said since we nailed every other hole, not every hole, and put the stucco right up to the window frame, not leaving a 1/4” gap, that they are not responsible for the window bowing.

Again, you do not follow installation instructions is it not Andersen's fault and I am not sticking up for Andersen specifically, this would be the same scenario for any window manufacturer.

Millworkman. I copied and pasted my comment to many posts so that anyone considering Anderson knows to make sure the installer follows the instructions exactly. I would have been so happy if someone had warned me so I could have caught it before our house was finished.

Alexsis, seriously? What about your shower waterproofing, HVAC system, vapor barrier - every single thing in your house has to be installed according to the manufacturer's specifications. Otherwise the warranty is void, at a minimum. If you're really unlucky your home insurance could be called into question. Be upset with your contractor, not Andersen.