From the post title, I am assuming you are comparing a W202 C Class to a same year 3 series BMW.
To me what makes an MB better than a BMW is long term durability, but I drive 60,000 miles per year and need the car to still be in good shape with several 100,000 miles on it. An MB is almost always superior to a BMW in this category. But if you are the average driver, you only drive 13,000 miles per year, making this a category that is not as important.
In the case of the 202, performance and handling wise, it is a dog compared to an equivalent 3 series BMW. If you need the long term durability and drive a lot, the MB would be a better long term choice.
If you want a nice driving C Class that will compare favorably, as well as offering long term durability, the 203 is the ticket.