Agree on season 4 -- it's possibly the most emotionally powerful, eye-opening TV I've ever watched. I find it less easy to choose a second-best between 1, 2 and

Agree on season 4 -- it's possibly the most emotionally powerful, eye-opening TV I've ever watched. I find it less easy to choose a second-best between 1, 2 and 3. 5 is dead-last, without a doubt.