Top 5 Sci Fi Shows Available Online

As a lifelong lover of science fiction it is incredibly hard for me to narrow down a list to the top 5 science fiction shows.  Feel free do disagree with this list, we are sure a lot of people will, all we will say is that if you haven't seen these and consider yourself a sci fi lover, then shame on you, and if you are new to science fiction then this isn't a bad place to start.  However, here goes.

1. Doctor Who, with David Tennant.  Our number one show has to be the seasons of Doctor Who with David Tennant as the Doctor.  Some of the best all time sci fi television episodes are part of this series.  We would list season 3 of the new Doctor Who series as some of the best TV, let alone the best science fiction.  "Blink", episode 11 is probably one of the best television episodes ever aired, across any genre. The last 3 episodes of that season, "Utopia", "The Sound of Drums", and "Last of the Time Lords" create one of the greatest multi-episodic stories in science fiction television.  If you have never watched Doctor Who start with Season 3 of the new series.
2. Battlestar Galactica, the new series, is in my number two slot. The new Battlestar Galactica series is very different from the 70's version, much darker, grittier, and more "realistic".  While this really isn't a series that you can watch out of order to easily, there is always a lot of backstory to it, season 3 is some outstanding TV. It starts with the takeover of New Caprica by the Cylons, follows through the human liberation by Galactica and Pegasus, and ends with the trial of then President Baltar, who was a collaborator.
3. Firefly is a "space western" television series created by writer and director Joss Whedon, of "Buffy The Vampire Slayer" and "Angel" fame. Set in 2517, after the arrival of humanity in a new star system. The series follows the adventures of the renegade crew of Serenity, a "Firefly" class spaceship. The nine characters live on Serenity and explores the lives of some people who fought on the losing side of a civil war and others who now make a living on the outskirts of society, as part of the pioneer culture that exists on the fringes.  It was a terrible shame that it only lasted one season.
4. Star Trek: The Next Generation was the first "spin-off" from the original Star Trek series.  The show was created 21 years after the original Star Trek show, and set in the 24th century from the year 2364 through 2370 (about 100 years after the original series time frame). The program features a new crew and a new starship Enterprise.  The writing and acting were top notch, it was the first, and currently only, syndicated television show to be nominated for the Emmy for Best Dramatic Series. It created some of the most memorable characters on television, from Picard, Riker, and Worf to Q and The Borg.
5. No list of top sci fi television can be complete without a nod to "The Twilight Zone", the original 1960's series. The Twilight Zone was anthology television series created by Rod Serling consisting of unrelated episodes depicting paranormal, futuristic, dystopian, or disturbing events. Each episode typically featured a surprising plot twist that was usually brought to closure with some sort of message. As well as being incredibly well written, directed, and acted, it was also notable for featuring both established stars such as Cliff Robertson, Ann Blyth, and Jack Klugman, along with younger actors who would later became famous, including Robert Redford, William Shatner, Burt Reynolds, Mariette Hartley, Shelley Fabares, and Ron Howard.