I'd take the Lexus - the power and features that it offers for its P3M price tag is a bargain compared to the Germans.
I don't like the exterior of the new C-class. The S-class design doesn't look good on a short and small frame of compact, especially the rear.
I've driven the 318d and felt that the 320d or 320i would be more rewarding for such a willing chassis. I haven't driven the new C200, but the old one was both fun and stately to drive.