French bows are supposed to be more flexible/versatile and German bows louder. It is easier to find a French bow teacher in the UK than a German one if that makes any difference.
Paul Chambers's teacher, Gaston Brohand, had to be ordered to teach arco with a French bow because he was anti-French arco techniuque and, until this point, had refused. Fortunately, PC played German but other players like Dan Pliskow in Detroit had to fight to get lessons and then had to put up with Brohan looking like he'd stepped in s*** for their whole lesson. Really motivational.