My CZ needed no trigger work, and they wear-in well, anyway.
The bore axis of the SIG is much higher and may affect your accuracy. Both guns are very accurate and reliable. I like the steel frame on the CZ, but the slide grasping grooves are easier to use on the SIG. The CZ's design leaves more of the slide deeper in the frame, and some may have trouble getting a firm grip on the slide to cycle it.
More gunsmith here are familiar with the SIG. No cops use it, officially, and that leaves questions, although the Czechs having been commies until about 1990 may affect buying attitudes.
I've never owned a SIG, but my son and his wife do, and he has a CZ-75B, too. They like both brands.
As for the lethality of 9mm ammo, the son has killed nine men in Iraq with nines, and had to shoot a few twice. He thinks that HP ammo would have helped.
That being banned in "civilized" warfare, he had to use NATO hardball. He now usually carries a .45 by preference. (No longer in the Army.)
BTW, he says that he had full faith in both the Beretta M-9 and the Browning M-35 if the gun is well maintained and used with Beretta, FN, or Meg-Gar magazines. Most M-9 problems are due to sloppy maintenaince or cheap magazines.
I find the SIG P-229 a little top-heavy unless loaded. I played with the DIL's. But her P-239 seems a good gun for its size. May buy one. (That's two models, not a misprint.) I think they also have a 9mm P-226.
The cops here mostly have SIG's and like them, although those who know much about ammo don't like the 147 grain JHP's they have to use. Those guys usually opt for the .357 SIG .
I load my 92FS with Federal 124 grain HST or Hydra-Shok ammo and feel pretty confident of stopping an opponent with a CNS hit.
I suspect that you'll find overall QC better in the SIG's, but the CZ works well, too, and is darned accurate. It is not as safe, for you have to lower the hammer very carefully, as on a Colt 1911. But CZ makes a CZ-75BD version that drops the hammer safely.
I want to try the stainless CZ.
