Justified (2010- )
This show caught my interest when it first started to air. I caught the first couple of episodes but then was distracted and never got around to picking it up again. I finally did and have been watching an episode a day for a while now.
The first two seasons were strong but then season three hit and I thought the show had jumped the shark. The parallels between the lives of Raylan and Boyd had reached comical levels. I kept with it though and season four quickly redeemed the series and it's been running strong ever since.
The promo I've linked above is also the best I've ever seen for obvious reasons. =P