Best sci-fi DVD commentary?
I'm someone who enjoys listening to a DVD commentary, but I think the Aliens commentary really blows all the other sci-fi commentaries away. It's just so much fun and worked out so well.
I remember the Ghost Busters commentary with the three guys' silhoulette was great also, must check it out again.
The Thing (John Carpenter and Kurt Russell) is another fun sci-fi commentary.
Some of the most disappointing sci-fi commentaries would have to be:
Star Wars: A New Hope (made up of separate interviews, not related to what happens on screen)
2001: A Space Odyssey (same as above)