Hi ismeto!

First of all I have to say, that I've never driven a C-Class SC or 1-series.

Personally, I'm not that great fan of the Sportcoupé - nevertheless it isn't a bad car, like coolraoul already mentioned. Your C 180 is two years old now...and I don't know if you would be that happy with a 116i. It's not that the car is underpowered or it would have a bad handling, but in my opinion you should keep your C-Class for a while.
Maybe, Christian can give you a tip - he has already driven the 1-series and many different C-Classes - I think, he can better compare both cars.