If I had to pick another brand of service weapon over Glock, it would absolutely be the Sig. I like the DA/SA transition offered by the Sig, as well as the location of the frame-mounted de-cocking lever. The Sig P220 I own shoots tight groups and operates flawlessly with whatever factory ammo I shoot through it. The precision manufacture of these guns is what you pay for, and the W.German made guns (in particular) tend to hold their value well.
I was once a Beretta guy, but found the lousy first-shot DA pull and slide-mounted de-cocker (G-variant) were a detriment to my best shooting. S&W Gen3's had the same slide-mounted lever issue, but a good DA (and even DAO) trigger pull. However, the S&W's had durability issues (the trigger play spring and fitted extractor being the Achilles heel of the design).
I carry a Glock on duty, and use the Sig as a range gun for a change of pace. My "M-glove-size" hands don't do well with .45ACP Glock pistols, so the Sig is my .45ACP platform. Yes, I know that the carbon-steel slide of the Sig can corrode if I expose it to the elements (abuse that a Glock would shrug off). I also know that Sig doesn't recommend sustained use of "+P" in the older P220's (a capability Glock shooters take for granted). The Sig bore axis doesn't phase me in the least, and, again, I enjoy my Sig for it's precision.
Metal-framed guns with lots of parts tend to cost more than polymer-framed pistols with a low parts-count. Sigs cost more than Glocks. I love both!!
Glock 17 (Gen1), 19 (Gen2), 21SF (RTF2), 26, 39
Glock Armorer (AC), Glock Instructor (IW)
Glock Advanced Armorer (AA)
Remington 870 Police Magnum, Benelli M1 S90
Smith & Wesson 13-2, 16-3, 36, 66-3, 681-3, 3000