Well JB I think it would depend on your intended purpose.
First off for calibre I would choose 9mm vs 40 or 45. Mostly because its cheap to shoot and easy to shoot. To get the best value and flexibility out of the other two calibers you would want to consider reloading IMHO.
If your interested in competing in IPSC then a CZ or a Glock would be a reasonable call, both have their advantages and disadvantages.
A Glock is easy to get going with and there are several tweaks you can do for shooting in in production division. But many dont like the feel of a Glock, they would prefer a straight backstrap.
A CZ would also be a good gun for starting in production division in IPSC and there are also addons that are allowed for those guns too. The only disadvantage IMHO is the DOA first shot, a stock CZ has a nasty DA trigger and without some work it makes for a tough first shot.
While I am thinking about it, the CZ 75 SP-01 is a great gun, but if IPSC is what you have in mind I would wait a few weeks to see the ruling from the IPSC world body on if its going to be allowed in production or not. You may be better off with a CZ75 or 85 over the SP-01. There is something about holding a gun made of steel that is much more enjoyable than holding a gun made of plastic
I do own a G17 and a CZ 75 SP-01 and I enjoy them both, and I would gladly recommend either of them as they are both great to shoot. IMHO the CZ needs some work and I want to change the sights on it, and once I get a holster for it I will be trying it in IPSC.
Now if your not shooting IPSC and just want one for target shooting, well its going to come down to your personal preference but I dont think you would be unhappy either one, heck I would give yourself a treat and get both!
Buckshot