Look around for a used model of either gun. Both are good guns, with the edge going to CZ, generally -- but you can stumble onto some great deals in used Witnesses, with great triggers.
The nice thing about the Witnesses is that caliber conversion kits are available, and in the older models (smaller frames) you could swap barrels between the 9mm and .40 models without having to change ANYTHING else.
The newer models (which have a larger frame) take separate top ends for most models, but are available in .22, 9mm, .40, .45, and 10mm. (I think you can find a .38 super for both styles.)
I've had a number of BOTH types, and liked them all. Don't have any Witnesses at the moment, but wouldn't hesitate to buy another, if the right deal or trade presented itself.