Both are excellent pistols. I own a Glock 26 and previously owned a Kahr K9. Here's how I see the advantages to both.
* Long track record of higher reliability. (Kahr has had very occasional glitches, though mine ran perfectly.)
* Trigger is better suited to really fast (defensive) shooting.
* Greater availability of mags, accessories, holsters, etc.
* Larger mag capacity and will take mags from larger Glocks.
* Considerably slimmer/trimmer than the Glock, and thus easier to conceal and more comfortable carried IWB.
* Feels better in most people's hands than the small Glock (though I find the polymer Kahrs actually too small for really good shooting, the trigger reach being too short for me).
Both guns have a good, low bore axis to minimize muzzle flip. I have a very strong preference for the short trigger action/reset of the Glock, so I eventually sold my Kahr and rely on the Glock design as my primary defense gun (when I'm not deployed). However, there is nothing wrong with the Kahr if you like DA trigger designs.