Falken 452's on the Benz. Not a bad tire, I really don't have enough miles on them to tell you for certain though. I have no complaints right now
Sumitumo HTR Z III's on the Audi. I actually really enjoy this tire. Quiet, pretty decent stick, still good in the wet. I must have 13-15k miles on them easily and they've still got pleanty of life left in them.
Hankook Ventus V12 Evo's on the M3. Don't like them at all, soft side walls, tall tread, really squirmy and don't feel planted at all. Should have gotten PS2's.
If money is no object I'm not sure there's a better street tire out there than PS2's. For a fraction of the cost I've been very happy with the Sumitumo's on the Audi though.