To stay Audi or go to Mercedes?

On the hunt for a family car and car to settle with for the next 4 years or so... I started searching for my perfect 4 door saloon... The battle is...

Mercedes C320 CDI vs Audi A4 (B8) 2.0 TFSI

Both cars on paper have similar MPG figures!!
Both have a 0-60 time of 6.9 seconds
The Mercedes has a V6 derv but sounds smooth anyway...
I'm used to a 2.0 TFSI having owned an A3 for some time... and being handy with VCDS.

Mercedes:
The only reason I considered the Merc was... when I closed the door it seemed like it was built to last and the ride was really wafty but on the down side I had no idea of what the car was doing... it did not feel engaging... although it seemed devastatingly fast due to the bags of torque it's not like I will be hauling a carivan or full compliment of passengers. 7G gearbox seems nice... The Mercedes salesman was a real douchebag... he has been dodging every single question I ask and just seems interested in taking a deposit to secure the car. I can find a decent spec'd C320 anywhere so the sales tactics are not washing with me... Perhaps that is why they have been a bit "off" with me?

Audi:
I like the look of the Audi A4 (B8) S-Line though... I drove it today... it has the familiar feel to me. Coming from an A3.. I am used to the handling characteristics... More fun to drive than the Merc. I know I can do more to it... when the time comes I can take it to APR... add air suspension if I want... and I don't have to worry about a DPF or NOx trap in 2015! The torque seems reasonable... Found a really nice one in Quartz Silver but want black... cannot seem to find any at main dealers. Need to finance it so gumtree and pre-loved are not an option... Not sure if the gearbox is CVT or S-Tronic. A lot of reviews on the internet state that a B8 from 2010 (10 plate) would be a S-Tronic...

I found an interesting thread comparing the Merc and Audi interiors: The MYTH about the Audi A4 B8's interior quality... | German Car Forum

So what is the better car? Does the Audi destroy the Merc?
Should I stay or should I go?

Battle between the heart and the head... heart says Audi and head says Merc.

Sorry about the long winded thread but any input appreciated.

Thank you all for your input and off topic opinions also welcome. I guess it goes like this... the balance between luxury and performance is the Audi. The Mercedes is just pure luxury... I'm officially on the hunt for a 2.0 TFSI S-line Quattro now.. I found a really good one at a main dealer but not happy with the quartz silver... want a black or white one.

For me I think what would make or break the car is... is the quality of the drive and handling. The mercedes is no fun to drive... half the time I hardly knew what the car was doing. The ESP did not fully deactivate when I tried to turn it off and I got a feeling it was always on. There were too many electronics interferring with the car so my input as a driver was all being manipulated by computers... I guess mercedes philosophy is... if it moves then put a computer or motor on it!

The Mercedes had a restful ride though.. seat comfort was good but I think the Audi hits back with lumbar support.. and still feels good.

I tried the coin toss too and my heart chose the Audi... I think the Mercedes is starting to look a little bit dated. Some say that the Audi dash is from a slight 70's look but I think the car is beautiful to look at. The Mercedes looks are heavy rather than graceful... the Audi looks out and out gorgeous from whatever angle I look at it... ready to buy when the right one comes along.

The Audi wins for me but I am going to take my time... It will be hard to track down a 2.0 TFSI Quattro S line in the right colour. If only Audi had some kind of mailing list or alerts.