Whatever company you decide on should be able to produce a rendering of each for you to compare and decide on.

Typically bigger grids are better because they give the window a larger feel and more open look.

+1 on WoW

5 horizonal and 5 vertical would be the industry standard for a window that size. That would translate to 36 lites or squares. I agree that larger squares give a more open look but you must be careful and consider the size of the squares on other windows in your house as to not make anything look out of sync.

It is 25 squares. 5 rows of 5. Other windows have squares that are slightly smaller.

The window you have now has larger squares than the rest of the windows because it is not at industry standard. This is why you need to consider how well the grids on a replacement window will match the patterns on the rest of them.

+1

Whatever you go with will need to match the grid size and spacing of any additional units you are replacing.

Of the multiple times we have had this conversation with clients, overwhelmingly the factor preset defaults wound up being the right choice and what the customer goes with.