Big fan of Game Of Thrones. Haven't seen series 3 of Walking Dead. Love any Attenborough documentaries.
S1 & 2 of Black Mirror were enjoyable. It's a UK series about the darker side of modernity and technology. Only 3 episodes in each series, but each is stand-alone and high concept... very dark, blackly humorous and thought-provoking. The first episode featured a kidnapper who had taken a member of the royal family hostage, and would only release her if the Prime Minister had sex with a pig (yes, you read that right) on live television.
Only recently started watching Breaking Bad, but I'm already half into season 3. It's the best TV series I've probably ever seen... the acting is extraordinary, the plots, style, writing, character development, moral questioning, suspense... everything is top-notch. A masterpiece.
It started off brilliantly and gets better and better. The metacritic ratings for Season 5 (99%) speak for themselves.
Best TV decision I've ever made was deciding to order the first series with a lovefilm free pass