The queston was favourite, so I'll take the Beretta 92FS. I've never mastered it to the degree that I have the Glock 17, but it ends up coming to the range with me every time. I just plain enjoy owning it, shooting it and showing it off. It is no where near the most ergonomic, size efficient or accurate, firearm I own, but it is definitely a favourite.
The Hi Power is an interesting firearm, but I never became enamoured of it, the trigger is not that good and the safety is small and not placed well for my hands. I'm sure if you gave me a Richard Heine Special I would change my mind though.
The Glock 19 is the most size efficient of the choices, I used to own one, but it is just a tool as far as I am concerned, not a 'favourite'.
The CZ75 is a fine firearm, but in my experience not as reliable as the Beretta, although the triggers are better and the grip is more suited to most hands. If I owned one, potentially I would prefer it over the Beretta, but I don't, so I don't.
The Sig 226 is, in my opinion an overrated gun. I've shot a couple, along with a P220 and I never understood what the hype was. Of course, realisitically they do have a better out of the box trigger than the Beretta, so this is just a matter of personal preference.
Anyway, that's my two cents. YMMV.