So I literally bit the bullet and purchased my first handgun. A Glock 23. It was more of a combination of opportunity and research than just a straight up hunt.
I made the same decision for my first handgun almost a year ago. It's still my only firearm, and I couldn't be happier with my decision. The best thing about .40 is that during the ammo shortage that started just before Obama got elected, I've been able to find FMJs or hollow points for my gun 99% of the time I looked. I still don't see any decent 9mm or .45 ammo, even decent FMJs, on the shelves locally.
I don't go shooting much, so I don't mind spending a little more on FMJ ammo. The best stuff I've found is American Eagle, with PMC Bronze coming in at a close second. For hollow points, the top four in my mind would be Federal HST, RangerT, Hornady XTP(TAP/TAP FPD or Custom line, but TAP has nickel plated brass for less corrosion while carrying), and Speer Gold Dot. Bonded RangerT and PDX1 are the same thing except the 180 Bonded RangerT is loaded a little hotter than the 180 PDX1. Hornady just came out with a 165gr loading of their Critical Defense line, which I have yet to try but would like to.
For hollow points I have and am satisfied with: 180gr Ranger T, 180 gr Hornady Custom, 155gr Hornady TAP FPD, 180gr Remington Gold Sabers, 155gr Hydra Shocks, and 180gr PDX1.
I prefer 165 or 180gr, but there are a few 155gr loadings I like, namely Federal Hydra Shock and Hornady XTP.
Thank you for your service and come home safe!
Edit: YouTube users andreleger2001 and tnoutdoors9 have some videos of home-made ballistic tests of several .40 hollow points. Also something to note, Speer Gold Dot 165gr comes in two loadings. The LE labeled boxes have two loadings, one rated at 100fps faster than the other loading. The civilian boxes of 165gr are rated the same as the hotter LE loading.