My favourite handgun out of the three I own is my 3rd gen Glock 20, which I bought about four years ago. It's nice to have night-sights and an accessory rail, as opposed to earlier models. It's also the only handgun I have with those advantages.
I've always been interested in the 10mm ever since I was a kid and had a fascination with the M41 Pulse Rifle (like the one in my sig) from Aliens which fired a 10mm caseless round. When I saw the G20 marked with firing 10x25mm AUTO ammunition, I just knew I had to have it! Then, I didn't know too much about the advantages and disadvantages to 10mm but quickly learned and am very grateful I bought it. It's a hell of a good cartridge, but as with most higher calibers, needs much more practice to become proficient. Likewise is a good powerful alternative to the good ol' .45 ACP (11.4mm).
The 10x25mm AUTO I would choose as my primary, any day, over what's common. Too bad it never took swing like it should have.