all three are pretty reliable, if not probably the most out of all the mass produced pistols chambered in 9mm.
i own a 92fs, but have shot the other two aswell. i think i can say that the glock 17 is the most reliable out of all 3, as it is the only one that has DAO/striker fired action or whatever.
if price, weight, ergonomics, and accuracy are of the utmost importance in your decision, then go with the glock.
the 92fs and the p226 are very very similar due to the fact that they are both DA/SA, heavy metal frames, relatively ergonomic (except for the safety on the 92fs, and the slide stop on the p226).
what sets those two apart i believe, is only the price. i was originally having a hard time deciding between those two pistols, but i went with the 92fs because it was on sale (and its also the ###iest gun of the 3 as well)
the DA pull on the 92fs is really bad, but the SA pull is really good. i doubt you'll be carrying it hammer down with a round in the chamber though, so it wont really matter about the DA trigger pull, unless you plan to de-#### your gun after each shot.
my $0.05
also from what people say about the grips on the beretta being too big, i have to disagree. i have small-medium sized hands, and i have no problem with shooting the 92. as long as you're not holding the pistol "surrey style", or shooting one handed with it, you should be good to go.