For me it is the dinner-scene in “the undiscovered country”.
SNW S01E04
Context is important on this one, but even without the rest of the episode around it I still really like it.
Spock: “The lower decks are beginning to buckle.”
Noonien-Singh, urgently: “The evacuation isn’t complete there’s still crew down there!”
Pike, with intensity: “Get them out.”
Spock: “Decks are collapsing, if we do not seal them off now loss of pressure could spread to the whole ship.”
Pike, pained resignation: “…Seal the bulkheads.”
Noonien-Singh: “Structural collapse on deck 22, we’ve lost one crew person.”
Spock, to Pike: “You made the logical choice…”
Pike, to Spock, quietly: “Why doesn’t it feel like that?”
Spock, to Pike: “For the same reason you made it: because you value life.”