For someone who's always LIKED the original show in a big way, I'm about as far from an all-out TREKKIE as you can get (which is no contradiction, of course. But I do have two favorites I can name.
Day of the Dove - It's about the first one I can remember seeing, it has that clever story and Michael Ansara, and of course it has Susan Howard as the exotic Klingon woman (thank heaven this was before ST decided to give them those crests!).
Miri - Among other things, how can you beat a juvenile delinquency story set on another planet, that makes a point of having Michael J. Pollard as one of the J. D.'s?