If it is in good condition - go for the Cannondale. It's a fairly rare bike in France and will be the envy of all your friends! Although the Sunn is pretty cool and will be bomb proof.
However, there are some excellent bikes going on here - especially the retro Konas and Oranges (never seen another Orange bike in France not owned by a Brit) and don't forget that shipping from the UK to France is quite reasonable and you could take advantage of the weak £ vs €
Canondale or sunn in my opinion. If it was me, I would get the canondale. Then, knowing my weak will power, probably get the sunn a week later too :roll:
The S Bike is lovely and practical. The Cannondale looks good value, but beware of old worn out Headshoks - expensive to fix. The Votec looks amazing and I've never seen one before - interesting, but not the most practical for what you need.
The Sunn, if it fits, would get my vote. The Revolt was one up the range from the Xircuit , nice riding bikes.
Here's a link for more retroSunn info. Good luck!