Both are great pistols. The Kahr has a very smooth revolver like trigger. The G19 is like all Glocks, like a rifle trigger with some initial takeup. I have a Kahr MK9 and a G19. I use the G19 for home defense and G17 too. I do my range and plinking with the G17.
If you have no experience with semi-auto's but you do with revolvers then you might prefer the Kahr. Generally, if you have no experience with handguns at all, I would avoid the Glocks until you get experienced. When you have a chambered Glock there is no margain for error. Keep your finger off the trigger, period, unless you intend to shoot what you aim at.
That is the only way to treat weapons in any condition, it is just extra critical when dealing with Glocks. Now some will poo poo this, but WE ALL have lapses in concentration. Just a fact of life. I wish Glock had a real safety. Then it would just about be perfect, for me anyway.
If you choose a Glock, practice picking up your Glock and holding it when not ready to shoot, by putting your index finger on the little indentation on the takedown mechanism. You should use that technique on any weapon, the Glock just has that neat little area to feel.
For what it is worth, my first handgun for home defense was a Ruger SP101. That was an excellent weapon to cut my teeth on. The consistent double action of a revolver or a pistol like the Kahr makes you think a bit when pulling the trigger.