each person that responds will have different experiences & respond based upon their likes & dislikes; I'll do my best to remain objective in my response; after not owning any semiautos for a time, I recently did some horse trading and acquired a Glock 17 in 9mm and a S&W Sigma in .40 S&W after handling a friend's Sigma in 9mm;
I have handled a Glock 19 in the past and liked the overall feel; the Glock 17 seems to have a slightly beefier grip (aka: the Glock 19 grip felt smaller); I like the overall feel of my 17 and the lower felt recoil that it has vs the Sigma in .40 S&W; I am not fond of the Glock's grip angle and must 'think' more about sight alignment or my front sight comes up higher than the rear sight (I am used to the 'more upright' grip angle of revolvers and other semiautos)
I bought my Sigma based upon a limited shooting session with a friend's 9mm Sigma; there is a noticable difference in recoil between 9mm & 40 S&W in the same framed gun; I am still on the fence about my Sigma in .40 S&W since I compare it to the Glock in 9mm I own;
Glock: lighter & shorter trigger, more recognized in the shooting world, more accessories available for them (sights, lights, lasers, holsters, mag carriers, etc), universal rail design (accepts more lights & lasers), awkward grip angle, very reliable, rear portion of cartridge brass not supported due to feeding ramp design, good fit-n-finish
S&W: heavier and longer trigger, less recognized in the shooting world, less accessories available for them, not a univeral rail (need adapter or specific light or laser to fit rail), more traditional grip angle (a bit more ergonomic for smaller hands), better support of cartridge brass, rougher fit-n-finish, more affordable at time of purchase
which one would I keep & which one would I part with: Glock: keep; S&W: go by-bye