SIG P226 (Mine has OVER 40,000 rounds through it)
1. Caliber: Not a .45, but ammo availability is excellent.
2. Size: Not too big (and pricey) like that pig SOCOM (and you can still suppress an extended P226), but the full size barrel allows 9mm to speed a little. I'd take the P228 for concealment.
3. Reliability: Like I said, OVER 40,000 rounds through it, and I can't remember the last time a had a feed problem.
4. Accuracy: There's no doubt that this is one of the most accurate pistols (in any caliber) right out of the box.
5. Capacity: Keep swapping those mags, Mr. 1911 [;)].
Somebody said the P226 is not a standard issue sidearm. Not for the US, maybe. But armed forces all over the world are using this pistol, and their choices are less political than ours.
Beretta: I owned one for two years and about 10,000 rnds, and shot it right along side my SIG. I that time, the 92FS broke two firing pins and the finish CAME OFF my lower (and Beretta wanted $190 to refinish it). No contest, SIG rules.
1911A1: Good gun, but I'm biased because my Springfield has last round feed issues. Plus, 8rnds capacity against 2000 Somalis doesn't cut it.
SOCOM: Big, expensive TOY. That's it.
USP: Not bad, but I don't really like the plastic feel of the trigger, and I've seen well-worn USPs with fire-control problems.
Glocks: Great guns, but I prefer the SIG because I have a deeper history with my P226.
Disclaimer: All of the above is merely personal opinion, and not meant as a personal attack on the character, familial lineage, or intelligence of fanatics of other persuasions. Flame On!