C5 because it's next down the model line from the C6............
Most people are snide about Citroen models because:-
1. They've never been in a modern one (all vintage ones are cool)
2. They've never driven one
3. someone in the dealership at Ford/Vauxhall/BMW/Audi/pub told them they were rubbish
4. They don't drive 500miles on motorway in one trip
Having driven >5 to between 125 - 200k miles each I have tested them. Thoroughly
I moved from BMW as a daily drive as I hated paying >£1600 per annum in insurance for 5yrs+ no claims in an 1800cc petrol with round badge.
I still own a  BMW for sunny summer days. OK it's a poor man's version - 3.18i with M10 engine. Oh and it is that very same fisrt car I bought. Nice