I handload so actually have no use for a 9mm except for a collector WWII numbers matching, Nazi marked, excellent condition German Luger. I prefer a 40s&w because 'bigger is better' for me and the cost difference between handloading for the two is negligible so why bother with the 9mm. I also like my 45acp and 10mm better still than the 9mm but both have a bigger frame.
In addition, the oft quoted, "the 40s&w is a high pressure rd and is more snappy", is a load of ***p. Both the 9mm and 40s&w are 35,000psi cartridges per SAAMI spec and a 9mm+P's SAAMI spec is 38,500psi cartridge which actually makes the 9mm+P a higher pressure rd than the 37,500psi SAAMI spec 10mm.
So, when people say, "my 147grn 9mm+P load is better than your 165grn 40s&w because it's more controllable." they are talking from a position of ignorance. I've shot both from a friend's G17 and my G22 as well as from his G19 (his CCW piece) and my G23 (my CCW piece) and the recoil 'snappieness' of the +P 9mm is higher.
Further, I use 180grn loads for my 40s&w SD pieces and the recoil, especially in my G23, is much more of a push rather than a snap. Followup shots comparing a 147grn 9mm+P and 180grn 40s&w, when shot from a G19 and G23 respectively, consistently show that the G23 is actually faster. And not just by me who is use to the 40s&w but also by my friend who owns the G19 we used for the comparison. (Much to his chagrin.)
Bottom line, the 40s&w, like the .357mag, 44mag, and 41mag all have their fans. I understand the appeal of the 9mm to the Leo community. It's favored over the 40s&w because of it's cheaper ammo.