All great guns! I have owned them all at some point.
The Glock 17 was my favourite oddly enough. The thing just pointed naturally for me. Throw in a 3.5 lbs connector and get a hogue slip on grip, and your laughing. I always preferred the older Gen 3's with the tennifer finish. Goodluck scratching those beasts.
The CZ 75B is very nice. If you can throw in a bit more and get the CZ Shadow, it is certainly worth it! I was never a huge fan of the realy tiny slides on the CZ. Hard for the larger hands to rack. Real solid and heavy gun though.
The Sig 226 is great. You can tell it is quality when you hold one. I feel they are a tad bit over priced though. With the high high bore axis, I was never able to have it point quickly for me. I would always take a few seconds to line up the sights.
The Beretta 92FS (M9) are wonderful. Real nice looking, solid gun. I loved mine. I couldnt get over the saftey being on the slide though. It drove me insane. Try and get a blued version. I found the parkerized M9 to show scratches very easily.
Hold them all, point them, rack them. They are completely different animals. Double action/ single action, Striker fire and polymer / steel.
You will learn over time and experience what works for you. It is part of the fun.
Good luck!