And like mdog and others have pointed out in various threads about Glocks, if you're gonna get just one, I say go for the 23. There's so much you can do with that bad boy in regards to conversion. Want a 9mm? Cool, buy a barrel and a couple of mags. Want a .357? Cool, just buy a barrel and drop it in. You can basically have 3 guns at less than 1/2 the price you'd pay for 3 separate Glocks in all 3 calibers.
You buy a G19 and guess what? You're stuck with a 9mm.
You buy a G19 and guess what? You're stuck with a 9mm.