I had a Glock 19 and it was my my first Glock. the first Glock I ever shot was a Glock 17 back in the late 90's and I didn't like it and I was mostly interested in a 10mm Glock because at teh time I carried a lightweight Colt Commander and much preferred calibers that started with the number 4 though I thought 9mm was OK.I would say either a 23/32 or a 27/33 for their modularity.
You can switch calibers with a barrel swap and increase capacity and grip size with mags and sleeves.
But not long after getting teh G19, I learned that could get teh exact same size gun an a caliber that started with the number 4, and balistics were similar to the 45. so a Glock 23 was the perfect replacement for the Colt Commander!
But that's not all. Having learned that I could get a top quality KKM conversion barrel for my G23, I saved all my 9mm magazines incuding a Korean 50 round drum mag and a couple of 33 round fun sticks and bought the conversion barrels so I could shoot the cheaper 9mm ammo. unfortunately there isn't any cheap 9mm ammo anymore but I still have the capability to shoot 3 different calibers after gettng a G32 factory barrel.
And that's what makes the G23 the Best All-around Glock, not only because of it's versatility, but became for me, it's the perfect size Glock.