If I had to take a Glock or a SIG, I would take a GLOCK, I dont need to go through my reasoning, read above.
However, I have to support the EERETTA suggestion. I have a 92FS, and I SWEAR by it. I would never trade it for any handgun, except maybe a MK23. Its a plain 92FS, and it is SOLID, has a VERY durable finish on it, and it is smooth as butter.
If I had to get a carry gun in .40S&W, I would eihter get a 96 w/brig slide, a 96 ELITE II, or a 96 Border Marshall.
I have shot about every beretta model, and they ALL functioned flawlessly, and had reportedly had more than 25,000 rounds through them all. Their customer service is wonderful, and other than HK guns, I trust no other gun company more than beretta.
Beretta and HK are currently at a tie for my personal list of best pistol makers.
That said, go for a 96, or a USP .40
also, if you look at the USP, it has the best of both SIG and GLOCK, and none of the negatives. Light weight(G), exposed hammer(S), accuracy(S), reliability/durablility(G), and is one bad ass looking gun.
The beretta however, is just solid, smooth and reliable, and durable.
Stick with Beretta or HK
If you must go sig or glock, get a glock