Babylon 5 - JMS wrote around 90% of the scripts while maintaining a coherent arc across five seasons. The first season is kind of cheesy as far as production value, but the stories pay off down the road. The second, third, and fourth season are incredible and well-worth the time.
Carnivale - I still hate HBO for canceling this, but the first two seasons are worth the time if you want to watch a stylish show of good versus evil set in the Dust Bowl during the Great Depression.
Doctor Who - Quality varies dramatically based on the writing and direction of each episode, but gems such as 'Listen,' 'Blink,' 'The God Complex,' 'Midnight,' etc more than make up for the hiccups here and there.
Hannibal - Excellent writing and great production value. I was skeptical when I first heard they were making a TV-series based on Thomas Harris' series, but after the first few episodes, I was hooked. Even if you've read the books, the story deviates enough from the established plot to keep you on your toes.
House of Cards - Kevin Spacey's best work. His character, Frank Underwood, would fit right in with the political landscape of Game of Thrones.
Luther - A BBC crime drama with Idris Elba in the title role. Ruth Wilson's protagonist is also well-imagined and reminiscent of a female Hannibal minus the cannibalism.
Quantum Leap - Science-fiction done right with a great focus on the two leading characters.
Sherlock - Stylish modern-day adaptation of the classic detective stories. Benedict Cumberbatch does a great job portraying Sherlock, and the show has received quite a few accolades for writing and acting since it started.
The Thick of It - 'The Office' set in the British government with Peter Capaldi (the current Doctor) as the vulgar and hilarious anti-hero.
The West Wing - I'm not a huge fan of Aaron Sorkin's more recent works, but the West Wing is a masterpiece and contains some of the best hour-long TV episodes I've ever seen - 'Two Cathedrals' and '20 Hours in America,' for instance, immediately come to mind.