(older) SIGS were considered to be as reliable as the Glocks (Glock is the gold standard for reliability).
The newer SIGS are not considered to be as reliable as the older ones. Sorry, just not.
The bigger difference is the trigger. The SIGS are gonna be DA/SA, which is OK, but it means you'll need to (certainly should) master two distinct trigger pulls.
The Glock will have the same trigger pull for every shot. and despite the folks who seem to dislike the Glock trigger (some of whom favor the Kahrs, or Kel-Tec triggers of all things), seem to miss, or not understand the concept of trigger re-set. (Which is why the M&P Shield is apparently getting some really good reviews from some highly experienced trainers-- it has a re-set trigger).
With the Glock, after you fire a round, you can (if you wish and/or have been trained) can release the trigger just enough to re-set it. This facilitates rapid fire (I'm not fast, but 6-7 aimed shots per second is readily achievable for me, depending on the distance). You don;t have to use the re-set technique, but it's a skill taught at most of the "big name" handgun training academies (including Thunder Ranch).
I carry the Kahr PM9 and/or the K9 as a BUG -- have for years. Smooth trigger? Yep. Good trigger for a self-defense weapon? Nope, not compared to the Glock, or to the SIG DAK trigger --- which is the point of all this trigger stuff.
If for some reason you feel compelled to go with the SIG (again, it's not a bad choice at all), be sure and pay extra for the DAK trigger. Then you won't have the DA/SA crap to contend with. It will be DAO, like the Glocks (and the H-K LEM), which is why 90% of the LE agencies that issue or approve SIGs specify that they have the DAK trigger. It's hard to find a major LE agency that still allows the DA/SA trigger -- too many ineffective/poor shooting results.
Glocks have a consistent trigger pull, as do the SIGs (with the DAK trigger), and the H-K's (with the LEM trigger), and the 1911's and the Kahrs and the M&P's and the XD's. This is important.
This post was edited on 11/15 at 12:59 pm