Tyres are all personal choice and we all havve our own opinions on them regardless.
I've had 2 x sets of each on the C63.
Conti's wore out after 5000 miles but, very sure footed.
PS4S - much better wear rate, very grippy but a softer sidewall which, you can feel the flex when pushing on (into a corner)
I upped the rear width to 265 (from 255) so, this may have changed things (ever so slightly). Just ordered another rear set of the PS4S (be here tomorrow) at the correct size (255) for comparison.
Let's face it, they wear out in no time so, whichever you choose will be replaced within the year anyway (mileage depending)
If you know a tyre fitter, I always use
www.camskill.co.uk. Great service and the cheapest on the net