MB would be a C32 AMG. My friend has a regular C class and I loved driving it for a day. Tint it out, throw some 19"s on it and call it a day. For BMW, I would go with a E46 M3 or E39 M5.
Benz. Parents are getting a S class this week. Beautiful car with a ton of room and comfort. But I'm in love with the E55. M3 is nice, and so is the 5's and 7's, but I personally like the benz's better.
I'd have to go with an M3 if I could find one in a reasonable price range.
However, my roommate just picked up a C230. He walked out the door with it for around $30k. It only has 201hp non-supercharged, but they're sweet lookin' cars. Could definitely see myself driving a nice silver one with tinted windows and some nice wheels.