GLOCK!!!!!!!!!!!!!!!!!!!!!!!!!!!! 40S&W gives more rounds than a 45acp and more power than 9mm. Sigs are nice but pricey. sound like the XD is nice but I have never used one. Also the Glocks sub compact you can use the compact and full frame mags for more ammo. and the compact can take the full frame size mags.
the glock 40S&W can be had in 22, 17, 15, 13, and I think 9 round mags.