MIchelin Pilot Sports. They were stock on both of my MB's, they perform like no other and have always served me well. They might be a little too oriented towards sport if you've been running touring tires. For an all season alternative, the Pirelli P-Zero B&S (their all season one, I'm pretty sure that's the name) seem to be great tires for the clients I have that want performance all season rubber.

On my winter rims I run Nokian Hakipulitas. On my CLK 55, the few times I would actually take it out in winter, I could barely get the rear to move around in heavy midwestern snow. A good friend of mine drives his E46 M3 all winter with the Nokians on it, and same story.