To paraphrase Spock, I'll have to cogitate on this for a time.

Ultimately had to settle with "Dark Frontier," but "Drone" was definitely right up there. "Relativity" I'd also rank fairly high, though I don't know if it's truly a Seven episode, more just a time travel episode that happens to feature a fair bit of Seven. "Infinite Regress" is a solid enough episode, but I feel other episodes stick the landing a bit better than it. "Someone to Watch Over Me" and "Human Error" are both great character study episodes, but I can also see how they might not be for everyone too.

Surprised neither "One" nor "Bliss" were in this poll, as they've always struck me as very powerful Seven episodes too.

chose dark frontier but surprised unimatrix zero wasn't included

"Dark Frontier" & "Someone to Watch Over Me"

"Relativity" & "Infinite Regress"

"Drone"

"Human Error", in that order.

Dark Frontier. As for the why٫ I'm not really sure. Logical analysis has yet to yield an answer as to why I like it so much٫ I just do.

Someone to watch over me

Dark Frontier