Glock 10mm will make you forget that .45 ACP exists.
OK, I know, I know. "Best" Glock is really a subjective issue, but, for me, the Glock 21 is, by far, my favorite Glock. Love it. Had a good range session with it yesterday. Here's an introduction with firing demonstrations.
Reasons I love it:
The large grip, I have big hands and I get a great purchase.
The site picture/radius, for me, is fantastic.
Trigger is my favorite Glock trigger, better than my other Glocks.
.45ACP - 'nuff said.
Great capacity: 13+1
The Glock 21: Introduction with Rapid Fire and Long Range Demo - YouTube
I owned a G21SF for a while, it was a nice gun and all, but so far the G34 is head and shoulders above the rest. On a good vision day (admittedly, getting less and less common), it will shoot like a pistol-caliber light rifle out past the far end of a football field.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)
I certainly would like some day to put a full size 10mm Glock throught its paces, but at this point, i have no need for a 10mm, and I kind of like to stick with either 9mm or 45mm which feeds my various pistols chambered only in either of those two...well, of course, there is the .45 Colt Ruger single action cowboy and the .22LR Ruger Huntsman Mark III, so.....well, it's the theory I try to abide by.