People often talk about grip on tyres when buying, I don't know about you lot but I bought my merc for luxury/quality rather than performance. I recently changed my bridgestones (Hard/noisey/wear rate) for some .... wait for it... Hankook K105's and the tyre noise, comfort difference is night and day. The car feels like how a Mercedes should do to me. Slightly less grippy in the dry when pushing on hard but on average little difference.
I first started using Hankook's when doing track days as I was going through performance tyres at a rate of knots. Compared to the goodyear F1's (another excellent tyre) they were less grippy but would always last the day and I could legally drive home on them again. They were very progressive, quiet (when not screeching) and a good wet dry compromise. I was using the K102's then, I've used the K104's since on various cars and for the Merc was looking at the new K107 (HP sports) but decided given the character of the car, the K105's (sports tourer) that are the evolution of the K102's are a better choice.
Avon's ZZ3's and Toyo's T1R (not S) I've also used and been good but Falkens I never got on with. Avoid anything called Nankang no matter how cheap it might be. Never used them, never want to, I've seen too many nightmares with them.
Another supplier worth a look, especially for trackday tyres:
http://www.camskill.co.uk/products.php?plid=m4b0s0p0
Just food for thought from the usual Bridgestone/goodyear/michelin performance/grip discussions.
Jim