WARNING: If you aren't caught up on any of the shows, its probably best to skip that particular paragraph.
1. Walter White (Bryan Cranston), Breaking Bad
The Walter we see at the end of the most recent season is so different from the Walter that starts the series as a bumbling, helpless chemistry teacher that its tough to believe they are the same person. But even early on we got hints that Walter's ego and his selfishness were going to keep leading him further down the wrong path. He's gone from completely sympathetic, to mildly defensible, to pretty out-and-out evil over the run of the show. It's a credit to the writers, and to Cranston, that every step has both been believable and in character.
2. Don Draper (Jon Hamm), Mad Men
It's no shock that the best character study on television has one of the best characters - the only surprising thing is not ranking Don first on the list. Don is so interesting because he seems to genuinely want to be a better person (obligatory Carousel pitch link because it might be my favorite 3 minutes of television ever) but his own demons constantly get in his way. Draper is such an icon of television at this point that I'm not sure its worth saying more - the character is incredible and finding a Hamm to play him was the most perfect casting of the last decade.
3. Carrie Mathison (Claire Danes), Homeland
I don't know that there's ever been a female character on television as compelling as Carrie Mathison. Incredible at her job and a complete wreck at the same time, her character as much as any of the terrorist/not-terrorist mystery is what made this the best new show on television this fall. You root for her despite her reckless, bull-headed, self-destructive tenancies because you know her motives are sound even if her execution is severely lacking. When everything falls apart in the penultimate episode, Claire Danes delivers one of the best performances I've ever seen.
4. Jesse Pinkman (Aaron Paul), Breaking Bad
Like Walter, it's tough to even remember the Jesse from season one as the character has been through so much and evolved so far since that time (though clearly he would have been better off having never met Walter). Jesse, more than anyone on the show, has been the victim of Walter's descent. While I want to watch Walter burn at this point in the show's run, I still want to see Jesse redeemed. That's saying a lot for a character that had this answering machine message in the first season.
5. Boyd Crowder (Walton Goggins), Justified
It's pretty well known that as originally written, Boyd Crowder dies in the pilot. But Goggins was so good and mesmerizing in the role that they instead turned him into Raylan's major adversary and three seasons later he remains one of the most fascinating characters on television. Crowder has taken on so many beliefs and personalities that it's probably impossible for him to keep track - he's been a white supremacist, a born-again Christian, a coal miner and a criminal mastermind. Crowder (and Goggins) sells each change so sincerely that its impossible to tell what Boyd really believes in.
6. Tyrion Lannister (Peter Dinklage), Game of Thrones
I have not read the books, so I have no idea what's coming, we are talking TV show only here. In a world full of strong rules who seemingly have no idea how to rule, Tyrion sometimes seems like the only person with a brain in the entire show. He is the perfect mix of humor, sincerity and wit. The way he maneuvers his way through the first season is simply awesome to behold, and it appears we'll have an even heavier does of the Imp in season two.
7. Peggy Olson (Elisabeth Moss), Mad Men
If Mad Men has a hero, its probably Peggy. She starts the show as this naive secretary who somehow gets seduced by the douchiest guy in the office (that's really quite a feet considering). But she manages to get herself moved over to Don's creative team as a copy writer and has slowly become a more and more vital part of the company since then. I know nothing about the time period, since I was -20 years old back in the 60s, but watching Peggy overcome the sexism and stereotypes of the time has been one of the only real 'feel good' arcs of Mad Men.
8. Daenerys Targaryen (Emilia Clarke), Game of Thrones
Thoroughly enjoyed her first season arc. On a show with so many characters and so much happening, it would have been easy for her story line to feel rushed. And while her transformation happens very quickly, most of it occurring in the first few episodes of the season, it manages to hit enough of the points to work.
9. Rayland Givens (Timothy Olyphant), Justified
Givens is the modern day cowboy, complete with the hat & the quick trigger finger. Olyphant does badd ass as well as anyone on television, but they've shown enough other shades of the character over three season to make him more than just a really cool gunslinger in a modern-day Western. Don't get me wrong, he's on the list more for being ridiculously awesome more than anything, but there's depth here too.
10. Tie: Dexter Morgan (Michael C. Hall), Dexter & Dr. Gregory House (Hugh Laurie), House
Cheating, I know, but these two characters are so similar I just had to group them together. Both are the title characters of long-running shows, and early on both would have been top 5 worthy characters on this list. But as the seasons drag along, the characters begin to get stale because they never change. Every season it seems like they will change, or things will change for them for a time, but inevitably by the beginning of the next year they are back where they started. It's one of the real issues with TV - you don't want to screw up what works and in the case of these two characters that ideal has made them far less compelling over time.
Follower Suggestions That Didn't Make the Cut
Pete Campbell (Vincent Kartheiser), Mad Men - In order to diversify the top 10 I tried not to get too heavy into one show. On the one hand I love the growth Pete has undergone over five season, but on the other hand he remains a self-entitled brat at times.
Roger Sterling (John Slattery), Mad Men - Hey, I love Roger Sterling as much as anyone. Slattery steals the show in almost every scene he's in and Roger gets all the best dialog. But as a character I would say he ranks fifth on the show alone behind Don, Peggy, Pete & Joan (who somehow didn't get mentioned at all by my followers).
Walter Bishop (John Noble), Fringe - Noble brings it in every scene, but there are so many versions of the character in so many alternate realities that its hard to include him since he's not really one character.
Rick Grimes (Andrew Lincoln), The Walking Dead - I enjoy the show, but the characters on The Walking Dead are pretty awful (the acting is mostly sub-par as well, which doesn't help). Rick is the 'best' in that he's the most fleshed out character, and the show did a good job of showing his continual struggle with how to lead his group of survivors, but there's just not enough depth there for me.
Shane Walsh (Jon Bernthal), The Walking Dead - I wanted to like Shane, but the writers seemed intent on demonizing him as much as possible. He felt like he was there almost solely to counter-balance Rick, but in a way that made him clearly the villain. There were ways to do Shane that could have made him a much more interesting character, and I'm disappointed that the writers chose to make him very two dimensional.
The Swede (Christopher Heyerdahl), Hell on Wheels - Cool character but not fleshed out enough to warrant inclusion. Also this show was a really, really terrible attempt at recapturing the magic of Deadwood.
Follower Suggestions From Shows I Don't Watch
Frank Gallagher (William H. Macy), Shameless
Lip Gallagher (Jody Latham), Shameless
John Reese (Jim Caviezel), Person of Interest
Harry Korn (Kathy Bates), Harry's Law
John Cooper (Michael Cudlitz), Southland
John Luther (Idris Elba), Luther
Nucky Thompson (Steve Buscemi), Boardwalk Empire
Richard Castle (Nathan Fallon), Castle
Thad Castle (Alan Ritchson), Blue Mountain State - The only person to mention a show I had never even heard of.