Coming from someone who doesn't like to invest a ton of time in TV...
My wife will watch much more than I do, and she knows if it's something I may have an interest in. I've abandoned more series than I care to count after one episode, because I can't sit through it if my mind goes somewhere else.
Anyway, top 4 in this order:
I'll throw in an honorable mention for the recent Sherlock Holmes series done by the BBC starring Benedict Cumberbatch, these are really well done.