Tough question : Tuchel is not progressing anymore, Dutt has been regressing, Streich is doing fine and Weinzierl hasn't proven yet that he can sustain this kind of performance.
So... it's a bit of a shot in the blue. If we go on talking about trainers, those in the BL are doing fine altogether with the noticeable exceptions that are Hyppiä and Keller. I would add that Lewandowski should go back at the head of Leverkusen, he was the best trainer they've had since Völler/Toppmöller.
Altogether, to me, Germany's third-best trainer is still Favre. He totally revamped Gladbach and maintained them in the first half of the table ever since. That's a mamooth achievement if we consider that Gladbach have long sucked ass as much as Cologne.
I agree on Lewandowski. At this point I think it's clear that he was the one managing Leverkusen last season.
Favre always chokes in the second half of the season, tho. I think Streich is better than Favre, but I think Weinzierl could end up being as good as Klopp or even better. What he has done in Augsburg is amazing