I'd like to nominate the Battle of Saturn Parts 1-2 in Space Cruiser Yamato where the Yamato leads the carrier fleet against the White Comet's fleet and the battle between the Andromeda and the magna flame gun. I saw that on television back in the late 70's and to me nothing has really quite topped it. The death of Captain Gideon and the destruction of the Andromeda really affected me.
For the detailed spectacle it presents. "Balance of Terror" from TOS wins for the sheer intensity of suspense. 
