The CZ is a good gun, no doubt, but the 5903/5906 is an American classic and a very capable handgun. I have several S&W 3rd gens and believe they are some of the most underrated guns available to today (even if you have to buy them used). My 5903 (alloy framed 5906) is a former Atlanta PD gun and has well over 20k rounds through it. Wear has been negligible, it still shoots great, is boringly reliable and is more accurate than I am. I have steered many people to S&W 3rd Gens and none of them have ever complained. I recently picked up a like new S&W 915 for $250. It has all ready proven itself to be an awesome shooter.
If you do get the 5906, MecGar makes a flush fit 17 round magazine for them this is every bit as good as factory.