The only thing in Trek, and I've seen every episode and movie and least once, that's ever brought a tear to my eye is Spock's death in TWOK. It was just done perfectly, two friends, the love, the loyalty, separated, unable to even touch... Just perfectly done.
I agree, it was perfect. But there are others that bring tears to my eyes.
the end of The Inner Light, and Picard and Daren's duet in Lessons
Lal's death in The Offspring
Tasha Yar's funeral in Skin of Evil
Geordi and Ro Laren's funeral (or was it just being planned? I don't remember) in The Next Phase, and RL at the end of Rascals
Benny's breakdown in Far Beyond the Stars
Ziyal's death in Sacrifice of Angels
(There were probably more, but I haven't watched DS9 in a very long time.)