Then it'd have to be 24. 24 is a one of a kind show, extremely well written and a great concept that actually worked compared to most TV show concepts.
Next is going to be Peaky Blinders. It's a crap story line and that but I watch it because I wish I was a Peaky blinder.
Then a special mention to You Better Call Saul. I've been watching it because it's a spin off of Breaking Bad, but I'm just not getting hooked into it. I'd imagine this will change as season 2 carries on though.