'BSG' -- Best Ever Sci Fi?

It's a little bit appropriate that "Battlestar Galactica" finale tonight (Sci Fi, 9 p.m.) airs one day after the 10th anniversary of the debut of "Farscape" on the network. Those are the two series that really defined the quality that the Sci Fi Channel has shown itself to be capable of.

As critics are writing their thoughts about "BSG" wrapping up after four seasons, my thoughts drifted to this: Is "BSG" the best science fiction TV series of all time?

Before one can say yes or no, one has to define sci-fi. Is the definition limited to shows set in outer space or centered on aliens? Or do you broaden the definition to include other fantasy elements, such as vampires? If you do the latter, then sci-fi TV has to include series that range from "Dark Shadows" to "Buffy."

Once sci-fi TV is defined, one has to define how being the best is measured. Is it pop culture impact? Because if that's the case, "Star Trek" would have to be the clear No. 1, thanks to four spinoff series, an animated series, 11 movies come May, and hundreds of books both fictional and non-ficitional based on the series.

Is it storytelling? Because if that's the case, No. 1 would likely have to be "The Twilight Zone," which changed the face of television and is among the best TV series of any genre of all time.

Is it longevity? Because then you have to start with "Doctor Who," which ran the first time from 1963-89, then came back in 2004 and is still running.

Is it crossing over into a mainstream popularity? Because one must then look at the success of "Lost."

What makes BSG so special for me, and what makes it worthy of mention in the conversation besides the great acting, terrific writing and very high production values, is that in one sense, it's the most pure sci fi -- science fiction as allegory and social commentary.

Few TV series in any genre have been able to so thoroughly capture the post-9/11 sensibility that runs through America, be it thoughts on terrorism, on human rights, on basic survival.

How fitting is it in how the Cylons are portrayed -- either as faceless, voiceless drones or as machines made to look like men, fifth columnists who have infiltrated all aspects of society like government, the military and the media.

'BSG' in its present form probably wouldn't have worked as a series 10 years ago, but in today's world, where our own economic survival is in doubt, 'BSG' mirrors it with the very survival of humanity, especially what survival means when there is little hope of a better future.

'BSG' brings to the table religion, cultural identity and politics, and allows the various debates to be spoken through the series' characters without getting preachy as well as staying within the context of plot.

The series has created some of the most interesting characters on TV, be it resolute leadership represented by Adama and Laura Roslin (Edward James Olmos, Mary McDonnell), to human frailty, ironically represented by many of the Cylon characters like Sol Tigh (Michael Hogan).

Perhaps no character captures the human spirit more than Gaius Baltar (James Callis), though unfortunately, it's an all-too-warped archetype that perhaps we don't want to admit is more of ourselves than we are comfortable with. Baltar is the ultimate survivor, always willing to blame someone else for his problems, and always willing to put his own interests first. Baltar is more pre-occupied with gaining power and sexual conquests, but how many people are there in real life who put aside their own self-interests at the end of the day in favor of pure altruism?

I could go on and on about the qualities of "BSG," but really, the highest praise I can think of is this: It makes you think. Not about plot twists or conspiracy theories, but about ourselves and our own lives, all the while telling the stories of characters the viewer ends up emotionally invested in. At the end of it all, I really want to know what happens to everybody.

FRIDAY'S BEST BETS: Besides the all-day marathon of Season 4 of "BSG" before tonight's finale, there are some other new things, though CBS is pre-empted by the NCAA basketball tournament.

Speaking of sci-fi programming, both "Terminator: The Sarah Connor Chronicles" and "Dollhouse" are new on Fox, beginning at 8 p.m.

Landry tutors Tyra for the SATs on "Friday Night Lights" (NBC, 9 p.m.) You keep trying with that girl, Landry. We're rooting for you.

Starz brings Season 2 of "Head Case" starring Alexandra Wentworth as a screwed up shrink with real celebrities playing warped versions of themselves at 10 p.m. It's followed by the debut of "Party Down," an "Office"-type show centered around a catering company, at 10:30 p.m. Both comedies have gotten a lot of critical praise.

On Saturday, "Ashes To Ashes" (BBC America, 9 p.m.) is all new, and all great in that returns the presence of Gene Hunt (Philip Glenister) to the small screen.

On Sunday, Kathy Ireland guest voices on "The Simpsons" (Fox, 8 p.m.), part of a whole new night of animated comedy.

"The Amazing Race" (CBS, 8 p.m.) travels to India, while "Cold Case" and "The Unit" follow with new episodes.

ABC has new episodes of "Desperate Housewives" and "Brothers & Sisters" beginning at 9 p.m.

"Kings" (NBC, 8 p.m.) didn't start out with a ratings bang, but it returns tonight, followed by "Celebrity Apprentice."

On cable, HBO airs the season finales of "Big Love" and "Flight of the Conchords," beginning at 9 p.m. and followed by a new "Eastbound and Down" at 10:30 p.m. Finally, "United States of Tara" (Showtime, 10 p.m.) is all-new.