https://us.glock.com/en/pistolssize comparison, they are nearly identical except for the width. G48 being thinner and lighter
mag options are better with the 19 (but not a big deal bc we are in hawaii)
aftermarket parts, holsters, lights, etc better on the 19. but 48 parts should catch up in time
people say that the 19 is better to get back on target quicker bc of the extra weight, and i think also due to the wider grip area. more surface area of the grip contacting your palm results in better control, as long as its not too wide for your hand and then you have to reach too far for the trigger and change grip to reach the mag release. but that is not the case for me with the 19
I have not shot the 48, so i cant compare it
I'm also along the lines or "if it ain't broke, don't fix it". or i like to go with what's tried and true, or what has been proven over time. thats why i got the 19 over the 48. and i'm not looking to CC it so slimmer doesn't matter to me
whatever fits your hand better and you can shoot better would be the better gun for you. but hard to tell without shooting it. bottom line is personal preference, either one will do the job