I'm in the same boat as the OP, my buddy raves about his Sig p320, and as a grown ass man I'm supposed to own a G19 too but they look pretty damn similar.
Does it all really come down to fit and feel?
Negative... at least not for someone who hasn't shot a gazillion rounds through a handgun. The Army adopted the P320 (in part) because:
-They decided a worthwhile criteria for selection, or at least a tier one category consideration, was how someone who doesn't know what a handgun should feel like thinks a handgun should feel.
-They fell for the modularity nonsense (nonsense because they aren't more modular than any other pistol, save the location of a serial number that really shouldn't apply to their considerations)
-People in the selection process also believe a single word of this article
The new handguns are built with an external safety, self-illuminating sights for low-light conditions, an integrated rail for attaching enablers and an Army standard suppressor conversion kit to attach an acoustic/flash suppressor, service developers said. Service weapons developers and soldiers...
nationalinterest.org
If short for time and haven't read it before, you're missing out on the single worst article ever written about a gun and about shooting all-in-one! Some of the knee-slappers (most courtesy the 101st):
Lt. Col. Knowsnada - "You can close with the enemy in close quarter combat and engage the enemy with one hand. It is tough to do this with the M9."
[Says guy who can't shoot an M9. Everything is tough to do well if you don't try to be good at it]
Sgt 1st Class Failedpistolquals - "With this weapon, you can change quickly from right hand to left hand. If you are shooting something that is not comfortable on your hand and can't get a comfortable grip, it is not as accurate."
[Accuracy is proportional to comfort... for something probably, just not shooting a pistol. "Can't" get a comfortable grip is a comment about the shooter, not the firearm. And, most pistols have a way to change the grips.]
Contract Writers - "The new handguns are build with [...] an integrated rail for attaching enablers [...]"
[what the hell is an enabler?]
Lt. Col. Stillhaventhadmycoffee - "It increases target recognition and increases capability with night sights."
Failedpistolquals (again) - "A standard pistol cannot change grips or allow a soldier to switch from a right-handed shooter to a left-handed shooter."
[Hold my beer]
Lt. Col. Differentguybutstillwrong - "It increases target recognition and increases capability with night sights."
[Night sights don't increase target recognition, Colonel]
Author - "The Army has been closely coordinating with the Special Operations community regarding training and development of the new handgun, given the consistency with which close-quarter combat is utilized by SOF."
[Clearly didn't listen THAT closely, considering almost every SOF unit is either issued a Glock, or fields a Glock regardless the contract (sorry Colt, MARSOC's guns are in a conex somewhere while they carry 19's).]
Feel can be an issue, but I've seen over and over again that people either think a Glock feels fine/good or will shy toward another pistol with a narrower/rounded front-strap. The common theme here is they're holding it wrong (seriously).
Points naturally? Irrelevant if done right. The grip could be backwards and not slow your presentation, sight alignment, or first shot whatsoever if the eyes are used to their potential. Reliance on anything else is trying to build mindless repeatability, which is okay to a point, but will hold you back further down the line. Brian Enos had one of the best thoughts on that, to the effect of "There should be little tolerance for habit in practical shooting."
Some guns do NOT fit, some guns DO hurt to hold correctly, but I just can't see someone who doesn't have tons of pistol experience making that decision to their benefit, save a bit of luck.
I do love the feel and pointability of a Triple-T S&W 19, though...