I thought "One" was superb - that's the one where the crew went into stasis, and Seven is left to look after the ship on her own. Cue masses of hallucinations and a wonderful psycho-chiller.
I was impressed with "Relativity" which I saw for the first time yesterday. It basically came down to "stuff causality and paradoxes - let's have some fun with time travel" - I appreciated the attitude!
I also rate "Deadlock" , "The Year of Hell" (although I didn't like the ending - and I know the guy that came up with it!) , "Destination: Oblivion" and "The Eye of the Needle"
Jon
"There are worlds out there where the sky is burning, where the sea is asleep and the rivers dream; people made of smoke and cities made of song.
Somewhere there's danger, somewhere there's injustice, and somewhere else the tea is getting cold. Come on, Ace, we've got work to do."
THE DOCTOR, "Survival" (Doctor Who)