I voted for Ruf, because I feel if I had to plunge my hard earned cash, it had to be in a company I can trust. Ruf 'feels' less risky to me, the most reliable partner. No empirical data to support that feel though.

Actually, personally, I'd prefer Manthey Motors.
MANTHEY MOTORS
A German company ran by a racing driver, that has a racing team and race cars, with knowledge crossing over to their customer department I presume. But again, no empirical data or first hand experience, just a feel