Life on Mars.
Do I really need to explain? Really? I’ve returned to this show quite a few times and every time I can never get over the fact of how gripping the opening episode is. It is an independent story, but really gets you invested in the characters and situation in a way that few other shows can. This isn’t a pilot in the stereotypical sense; in the industry calling the first episode a “pilot” is a way of making an excuse for lower-than-expected production values, shaky acting, and less-than-water-tight introductory narrative. But in this first episode, Life on Mars is already in full stride, and I think that’s why you can’t turn away after watching the first episode. You simply must watch the whole series.

Runner up:

Doctor Who, “The Eleventh Hour”.
While “The Eleventh Hour” isn’t a pilot in the dictionary sense, this is the first run of a new show runner, new Doctor, new companion, new title sequence, new director, new executive producers … Really, this is the pilot episode for Team Cardiff.2, spearheaded by Steven Moffat. And what an introduction. Matt Smith was brilliant. Karen Gillan was gorgeous and sassy. The story was clever and fun. Really, it was a fantastic starting point for a new crew and new direction for Doctor Who. And that’s what’s so brilliant about Doctor Who; it’s the same show, with the same main character, yet can completely reinvent itself while maintaining its sameness.

Ashes to Ashes.
What a weight to carry on its shoulders. Rounding up, explaining, and ending two of the most fantastic television series ever created. And finding a way to answer questions that is reassuring, satisfying, and lovingly crafted. And superbly executed by an incredible cast of versatile and talented actors.

Life on Mars / Ashes to Ashes.
Because so much of the main cast is shared, I’m splitting this between Life on Mars and Ashes to Ashes. Seriously, the cast is simply amazing in these two shows. The BBC is like this incestuous pool of ridiculously brilliant acting talent. And it doesn’t hurt that the writing for both shows was spot-on fantastic. And just look at the pretty. So, so much pretty.

Life on Mars/Ashes to Ashes.
At this point you really can’t have one without the other. I mean, you can watch Life on Mars on its own, but you [possible spoiler deleted]. And you can watch Ashes to Ashes on its own, but you’ll miss all the references to Life on Mars. There is so much pretty to look at, so many clever plots, characters that you can’t help but adore regardless of moral grayness, and did I mention the pretty? There’s lots of it. But seriously, these are incredible dramas that suck you and and keep you completely intrigued from episode to episode.