Oh, how do I pick just one? I’ve been a die hard fan since my mom let me stay up late on Thursday nights to watch the premieres on NBC (then a few years later I got to watch them ‘like new’ again when we got a color TV and I realized the victim of the week usually wore a red shirt).
As a kid, I’d have to vote for “The Trouble with Tribbles” and “A Piece of the Action” though over time, I think my tastes migrated more toward “Balance of Terror”, “Mirror, Mirror” and “The City of the Edge of Forever”
I never liked “The Lights of Zetar” The special effects of the possesed woman dying gave me nightmares and I remember being scared by that one to this day. (Yeah, I know it’s kinda cheesy by today’s standards, but to a 3 year old it was really eerie.)
My all time favorite episode from the entire Star Trek Franchise is ST:TNG’s “The Inner Light” where Picard is zapped by a probe and lives out his entire life as a member of a race on a dying world.
BTW, Britanee: I’m also a big fan of Stargate-SG1 and Atlantis (and have the entire set on DVD) so there’s no reason you can’t like both and if you start a Stargate related thread I promise to post something positive 😉