Between your two choices (since Glock seems tacked on), I would go with the CZ. I have shot Berettas much more than I have a CZ75, but I still prefer the feel of the CZ line. I haven't handled a compact, but the full-sized model fit me just fine. IMO both of the full-size models are on the large side for CC, but the compact would definitely be more manageable. Makes sense though given they were designed to be a duty weapon, and not built from the ground up with concealment in mind.
As for why I like the CZ, I prefer the grip as well as the options you have (DA/SA, SAO, Decocker, etc.). I also like the location of the controls being on the frame, as opposed to the slide. The last part isn't a deal breaker as I can disengage the safety just fine on an M9, but more of a personal preference.
Also, I don't think parts will be hard to come by for either model. You have your typical aftermarket choices, but nothing on the level of say a Glock or 1911. If you really wanted to customize your gun, there are better choices. Either way, if you want a DA/SA, double stack 9mm with a metal frame either one should suit you just fine.