TWOK, we all know which scene!
When Data and Lal are saying goodbye. GOD, it KILLS me every time.
The Inner Light for obvious reasons.
Picard's scene with Crusher after he mind melded with Sarek to help him finish one last mission.
Spock's face at the end of Unification.
Kira talking about her father after Tekeny Ghemor passed away. My own father is in failing health due to Parkinson's, and today that scene gets me more than it did when I was a teenager. I know how Kira feels now. Growing up sucks.
Just about ANY TIME Odo gets that heartbroken look in his eyes. Doesn't matter what the situation is.
That hug at the end of The Begotten.
The poor baby Changeling...
Kira telling Odo she doesn't care how he looks when he's all sick with the morphogenic virus and Odo saying he doesn't want her to see him die. (So glad he didn't!)
I WILL ALSO ADMIT...I cried for joy when they finally kissed! And that aurora borealis moment in Chimera is another happy tears moment.
Neelix forgiving Jetrel at the very end.
The Doctor's holographic family...zomg.