I would choose the TSX. I have driven both. The C300 is boring to drive. It is too quiet and smooth. It is teh kind of car that makes you fall asleep at the wheel. The Acura feels much faster and is much more fun to drive. I also prefer the looks inside and out of the Acura. The Acura also handles better and is much more reliable. Acura is probably the most reliable luxury car in the world. It is also cheaper to maintain and gets better gas mileage. The C300 feels like a big car to drive.