I presume you are dealing with distributor/installers. Perhaps it would be appropriate to ask the companies for references you could contact to inquire about their satisfaction with their windows and the installation. If any are reluctant to provide references, you could mark them off.

On the other hand, there is nearly $4,000 between the high and low quote. Something doesn't seem quite right.

What were the different U factors and SHGC's of each of the windows?

What were the differences when you compare air infiltration ratings?

What is the difference in the grade of vinyl each one used? What differences were there in the die used to extrude each window?

How about differences in hardware and balances?

Which ones used spiral, constant force or block and tackle balances?

What were the differences in the spacers used in the I.G. unit?

What glass manufacturer does each window company use and do you understand the differences between the different glass options?

Do you understand the added benefits that heat mirror adds as opposed to double pane glass?

If you don't at least know the answers to "ALL" these questions then you wasted the time you spent with each sales rep and IMO are not yet prepared to make an informed decision as to which window is the better value.

I am not a pro and have little vinyl window knowledge but want to share another perspective regarding wood windows.

There is no reason to use wood windows that are not clad on the outside unless there are architectural concerns or there are needs to change colors in the future. Many companies make wood windows that are clad on the outside. The cladding can be factory-painted with a host of colors. While there are differences in cladding material, they are generally quite durable and can endure quite a bit of abuse. Our aluminum clad exterior has put up with hail, balls, bike tires, frisbee, occasional gravel strikes and high heat in full sun. Frequent painting of the exterior of a clad wood window is no longer necessary. The interior wood is exposed and can be stained or painted. Good paint and stain can last for a long time (5+ years).

"Little panes" or true divided lites has not been a standard for a long time. TDL is now an expensive custom option. All modern windows, wood or otherwise, now use one large piece of glass. The grids are now optional and they can snap-on/-off and you can pick interior grids only or exterior grids only or both. You can even ask the manufacturers to add spacers between the glass to match the grid design so that visually, when grids are on, they look like true divided lite but it is still one piece of glass. With grids off or no grids, they are relatively easy to clean; there are no little panes to clean unless you specifically custom order them.

There is no reason why you cannot use normal clad wood windows if wood is your preference.

Now to share my limited knowledge of vinyl windows. Having learned from many pros here, the differences are in how they are joined together, what sort of energy-efficient spacers they use, how big is the air gap between the exterior and interior panes, how thick are the glass, how the frames (wording?) are made so they are strong and yet energy efficient and whether it is recycled vinyl or new vinyl.

We have learned, through first-hand experience, that some dealers will order thinner glass and charge you thicker glass price. We also learned first-hand that some windows have less air space, therefore are less efficient. Use of metal spacers may not be as effective a thermal break as that of newer space age spacers (super spacer??).

If you are in a wildfire-prone area like we are, vinyl exterior can weaken and potentially melt in a wildfire. You also want to use tempered glass because it is tougher and able to withstand heat stress better than normal glass. Other than that, we still have two Milgard vinyl in use and they have lasted 10+ years now with only simple problems. One warped and became hard to crank to open. One no longer slides easily open. Milgard has lifetime warranty and will replace them for free but we prefer wood interior and aluminum clad exterior now. We will replace them soon but otherwise quite satisfied considering the price we paid and how long they have lasted.

Good luck!