I like the 9mm, and before I read this thread, I thought I still had a complete set of daddy parts...but now I’m not so sure.
The 9x19 is a NATO round.
Our entire military will likely not switch to Sig in an instant, with guard units likely to take up to 10 years to fully transition.
We likely have inventory of 9x19.
9x19 can hold more rounds.
Now this last one is REAL important for all the John Waynes out there who have to push a wheel barrel around to hold their genitals: The military service pistol is for personal self defense. It is a weapon of last resort.
Who carries a pistol:
Pilots
Armored Crewmen
Staff officers
What to infantrymen who kick in doors and shoot monsters in bodyarmor carry? M4, M16, Grenades, etc.
9mm should do just fine.
Tunnel rats
Vietnam-era M60 machinegunners