Which suppresor device will be use for 2pole AC contactor 240v coil voltage in coil as well as contact side?
There are cons and pros for each type of suppressor. Since you use the AC then the diode as well zener+diode are excluded. You can choose between RC snubber and MOV. Usually the MOV suppresors are embedded into a contactor itself, you need just to order the correct one. RC snubber is more bulky and has to be mounted as add-on.

You can find details on: Simatic contactor



Using RC snubber on contacts, will produce a leakage current trough. A device connected to the contactor will always have some voltage, also the electric tester will show you a voltage presence even when contactor is disengaged. Usually you won't find any real application with suppressor mounted on switching side, it is done only for high inductive loads.