Back to the original question. I've got several 9mm guns and a couple of .40 Glocks, a G23gen3 and a G22gen4, as well as other calibers. I sold off my G27gen2.5 years ago. I'm mainly carrying 9mm, lately.
Consider, being in California, you may also be limited to 10-round mags (or you may not depending on one's situation). Therefore, would you want to carry a Glock 23 with only 10-rounds, instead of a G27. Regardless of capacity, the G23 may provide a better grip for some folks. The HK line of firearms may have similar size issues, such as a P2000 vs. a P2000SK.
One thing to consider regarding the Glock 19 is there have been reports of its 10-round version of its magazine as being inconsistent as to its reliability in feeding.
Narrow down your choices and caliber and re-ask the what-to-buy questions. Some people go back and forth over what to buy for over a year, then end up buying something not even considered in their original post.
Me? I'm usually carrying a Glock 19gen3, with 15-round mag, or sometimes a SIG P229R 9mm, also with a 15-round mag (P226 mag with X-Grip floorplate). I said "usually" as I could be carrying any handgun and at a given moment and, actually, not just only one.