If you want a similar ride to standard, then fit OEM shox. If you want different handling/comfort, probably best to consult someone who knows about these things, otherwise you could upset the car's handling.
I consider them to be a service component, like brake discs, eventually to be replaced with a new set.
After market shocks come in two varieties: extra sporty for don't hit the cat's eyes if you have loose filings; cheap and nasty for folks that don't want to cough up for OEM.
S210 has self-levelling rear = OEM. Do you have ESP? = OEM.