I have no idea.... I'm inclined to say Christian Gross but I think he may be swiss (which is close enough...)
Ralf Rangnick - left Hoffenheim to go to Schalke, but has left them due to ill health - Post Viral Fatigue Syndrome apparently.
For me, it has to be Jurgen Klopp, the guy plays such good footy and his players love him and his style. He is a bit down to earth ( Not always a fancy suit on, but track tops normally). Does things in practice like 11v11 in half a field to get the players to think quicker, play quicker, move the ball quicker, so when they go to the full size the time and space seems endless. He also brought youth up the ranks at BVB and bought very astutely with Barrios, kagawa, Lewandowski to name a few. He would be perfect for us and I would jump for joy if/when this happens ( obv not for another year or two).