I understand that you say that these are the only two choices and nothing else, but do you realize that one is a 9mm and one is a .40. A better comparison would be K9 vs. G19 or K40 vs. G23.
Anyway, I voted K9 not because I like the 9mm better than the .40 (although I do), but because I like the Kahrs better than the Glocks. I like the all stainless steel construction and the slim single stack grip. I like the ability to put on custom grips if you like. I like the Kahr trigger better as well (especially in Elite 98 format). My two Kahrs (a K9 and an MK9 both Elite 98s) have been a real pleasure to own...much more so than any Glock I have ever had...and I have owned 5 Glocks, including a G23. Glocks are good guns, but strictly utilitarian. Kahrs have a little class to them.