The handguns in the CZ line employ 2 different primary or active safety mechanisms: the manual safety or the decocking lever.
Both of these designs are good safety elements, but both have advantages and disadvantages depending on your perspective or intended use.
If you are intimately familiar with 1911 style controls, and it is second nature for you to flip the safety lever up after chambering a round and to flip the safety lever down after drawing from the holster and before taking the shot, chances are the models incorporating the manual safety lever are for you.
In single action mode, the models equipped with a safety lever provide a consistent light short trigger pull from the first to the last shot, as a result of this feature, these models are also generally preferred for target, plinking, and most competition disciplines. Some people will prefer the safety lever equipped models simply due to the versatility they give the shooter. With the safety lever equipped versions of the CZ 75 family, the shooter has the option to carry with the hammer back and safety on (cocked and locked) or after manually decocking.
The vast majority of us don’t have the experience of shooting the tens of thousands of rounds necessary to train ourselves to almost subconsciously flip down the safety lever before taking the first shot, nor do we all have the opportunity to fit the weekly range sessions required to keep current with skills we have developed in the past into our schedules today. For plinking or casual target shooting, this isn’t a big deal, but when under the stress of a defensive situation, remembering to take the safety off is critical.
The models equipped with a decocking lever are, in most cases, the best choice for most shooters wanting a handgun for defensive purposes. With the decocker models, you must remember to decock the hammer after chambering a round and before holstering, but when placed in a defensive situation, there is no safety lever that you have to remember to disengage; the primary safety element of the decocked handgun is the longer heavier pull of the double action trigger.
If you aren't sure which side you are on... Safety or Decocker.... take a look at the CZ P-07 Duty. The "Duty" comes with ambidextrous decocking levers installed but it includes a set of manual safety levers in the box. By following the instructions in the owners manual, it only takes about 5 minutes to do the conversion.