I always liked the episodes when Troi's Mother comes on board. You get to see Troi go to pieces and absolutely almost go insane
But my favorite one is always is going to be "Naked Now." and "Second Chances"
Classic quote. (from Naked Now)
[trying to seduce Data]
Lt. Tasha Yar: You are fully functional, aren't you?
Lt. Cmdr. Data: Yes.
Lt. Tasha Yar: How fully?
Lt. Cmdr. Data: In every way of course. I am programmed in multiple techniques. A broad variety of pleasuring.
Lt. Tasha Yar: You jewel. That's exactly what I hoped.