How to decide between a French or a German pattern chef's knife?
It really is an issue of personal preference.

If you prefer a rocking motion, the German profile suits your style better; if you are a push-and-slide person, the French profile is more suitable for you.  It also possible to find models at various points within the range.

See this Chef Talk thread for an in depth discussion (with diagrams at one point). The original poster concludes, quite correctly in my opinion:


  But... let's keep our senses of perspective and humor.  A German knife
  won't turn a good cutter into a bad one, and a French knife won't do
  the opposite.  Both profiles suit the classic, European and American
  styles of food and knife skills.  It comes down to taste and training.