I work at a gun range, talk to a lot of people about a lot of stuff including our gunsmith. as far as reliability, people are rougher on guns they don't own, so I have to take into consideration what our ten year old rentals look like. basically, the glocks still work. all of them.
My understanding from several law enforcment agents and just old shooters is that sig has lost it's quality. The biggest sig fans I know wish they had there old guns, and take it easy on there new ones. this explains why we have tons of problems with the sigs we rent out half as much as the glock.
This doesn't mean sigs are bad guns, if a pretty gun with a useless decocker means more too you than absolute reliability, then by all means, by a sig.
The other side of it is how does it fit your hands. Glock does have a different grip. if it's not comfortable and you can't point and shoot it, then buy something else. who cares if it's reliable if your shooting over the bad guys head or at his feet. find a range that rents a lot of stuff. shoot them all. then, whatever you buy, clean your gun. practice shooting, and if your still worried about reliability, buy a revolver