I would defiently watch a whole series focused on the adventures of Person of Interest's Shaw and Root. And Madam Vastra, Strax and Jenny really do need their own series ASAP.

The Doctor (Any Incarnation but mainly the ones after the Time War) Because he's had to deal with the knowledge that he destroyed his own species. Obviously, the events of TDOTD suggest otherwise, but they - especially the Ninth Doctor, don't remember what happened. He's living with the guilt that he took the lives of…

Battlestar-frakking-Galactica (2003). Most recent discovery that has become my favourite show - currently working through Season 2 and loving the hell out of it.