Low sheen medium colors will show the least wear and tear. High sheen and/or dark colors show everything.

I just had Bruce floors put in and these were 2 of the 3 colors I was looking at. The other was Saddle, which is what I ultimately went with. If there had been a color that was a 50/50 mix of Saddle and Fawn I would have gone with that one, but Fawn was too light for me.

Gunstock is redder, and is red oak while Fawn is white oak and IMO more of a 'neutral' brown. Fawn might be a tad bit lighter than Gunstock - it was lighter on the sample board I had but it's hard to tell whether it was the piece of wood vs the stain color in general. Fawn does not seem to be a popular color because I couldn't find any photos of it other than the marketing photos, which all seem to be Photoshopped anyway. There are a number of different photos of Gunstock if you do an image search, though.

Really with these 2 colors it's mainly a question of whether you want a more red-toned brown or a yellow-toned brown. With the cabinet and granite colors you have it could go either way, it'd just be a matter of personal preference. In my case red tones would not have gone with any of my decor so I purposely avoided them.