Who is your favourite (relatively well known) animal behaviourist/trainer?

I have just watched a recorded seminar about dog on dog reactivity by Patricia McConnell which I really enjoyed. Her knowledge alongside her manner made me want to listen to what she had to say and I came away feeling like I had learnt something that I could pass on to clients at the training company I work with. Is there a trainer/behaviourist that you, not only find engaging to watch but also who’s theories and knowledge you trust? On the flip side, who’s theories and training techniques do you disagree with?