I would say go for the c270cdi....as for price it is so much cheaper than the is.
If your gonna compare an e270 cdi with is for the same price you will get a much bigger car.
But on that note it depends what you will be usintg the car for.
If you are older than me so insurance cheaper...does that not matter.
how many miles you do?
size of family?
what type of driving you do?
whether you want to bit more individual or that doesnt bother you?
There are so many reasons why you choose over the cars.