Without further adieu, here they are (in chronological order):
1. Collision. (Season Two Episode Eight)
Giacchino's score, as usual, doesn't help in avoiding crying. There's just something about seeing their reunion, so soon after meeting Bernard, after listening to Rose's undying faith throughout the entire first season. Rose and Bernard's love for one another is easily one of the most beautiful stories on LOST. I'm not a huge Ana Lucia fan, and by that, I mean I enjoyed watching her die. But this episode is one of my favorites, aside from reuniting good ol' R&B.
2. Through The Looking Glass (Season Three episode Twenty Three)
Charlie's death shouldn't have been shocking after how much they hinted at it. But when Patchey sets off that grenade and the room starts to flood Giacchino's score kicks in brilliantly once again and our hearts break as we loose our third original cast member. From 'Not Penny's Boat' to the final shot of him floating lifelessl, Charlie's death is a killer.
3. The Constant (Season Four Episode Five)

Penny and Desmond... the only couple (other than R&B) that are actually worth rooting for. After all the topsy turvy time shifting/jumping fiasco's we've seen desmond go through (i.e 'Flashes before your Eyes') 'The Constant' raises the bar once more. And when he picks up the phone and dials Penny's number... the tears start to roll freely. Penny had it right when she said "All we really need in this life is one person who truly loves us"......Henry Ian Cusick and Sonya Wagner rock this scene and to this day I can't help but reach for the tissues when watching this ep.
4. Ji Yeon (Season Four Episode Seven)
Is Jin dead? Upon first viewing this episode sure does elude to that. Regardless of whether or not you were spoiled, or simply refused to believe they could kill of a main character without providing any clear cut evidence, watching Sun give birth to Ji Yeon and then visit Jin's 'grave' with Hurley is still painful to digest. Yunjin Kim kills through the whole episode. And Giacchino's track 'Ji Yeon' is tear worthy in and of itself bearing quite a resemblance to his other emotional tracks 'Life and Death' and 'There's No Place Like Home.'
4. The Little Prince (Season Five Episode Four)

5. Whatever Happened, Happened (Season Five Episode Eleven)
I know people love to hate on Kate episodes but I for one LOVE THEM! Sure some of them aren't as strong as others, and I fault the writers for that (Even though I will follow the geniuses that are Darlton & co. to hell and back) for using her episodes as a place to advance the love triangle more than her character at times. With that being said, Kate's scene with Carol Littleton and her goodbye to Aaron get me every time. Evangeline Lilly was superb in this episode, and it truly shows just how much her craft has grown from season one.
6. The Incident pt. 2 (Season Five Episode Seventeen)
LOST is great about changing the way I feel about people/scenarios at the drop of a hat. When I go back and watch season three I'm always amazed by how much I HATED Juliet at the beginning. Somewhere along the road I ended up loving her. It wasn't her first flashback, or even her second (I don't think), but somewhere between then and the beginning of season five I truly became invested in her. Not only does that piss me off, but its a true testament to Elizabeth Mitchell and the material the writer's provided for her because usually when I decide that I hate a character, there's no turning back (I'm talking about you, Ana Lucia). Now at the beginning of this season the writers started to place little signs that the Suliet train was leaving the station with a destination of our living rooms. At first I was outraged. But somehow, once again, I became OK with the idea. At face value of course. When 'La fleur' aired, I thought, 'how cute'. Then the end of 'Lafleur' happened, and Sawyer went on this huge rant about how he 'had a thing for a girl once' blah blah blah and how he 'can't even remember what she looks like' I had to call BS on that one. I don't care who you are, or if you loved her, but I find it hard to believe that anyone who spends 100 plus days with someone who looks like Kate and even is just friends with her is going to forget what she looks like. In fact, I'm sure if you'd asked Frogurt (if he'd made it past the flaming arrows incident) three years later what Kate looked like he would have been able to paint a fairly accurate picture. Anyways, Sawyer's BS gets called out soon enough as the 316ers roll up with JIn. That's not the point of this is it? I've clearly lost my way... Oh right, The Incident. As I was saying Suliet slipped into my heart, but above that, I love Juliet. And watching her fall to her doom is heart breaking. Josh and Elizabeth's performances were fantastic (the whole reason why they were able to weasel their way into my heart in the first place).
7. LA X

Leave it to Darlton to make us live through Juliet's death not once, but twice. The second time was even worse, almost cruel... wait, not almost... it WAS cruel. Josh Holloway owned the scene... and stole my heart for what was most certainly not the first, and definitely not the last time. I remember watching this at Sunset On The Beach for the first time with fifty gajillion other Losties and crying. At first I was embarrassed, but then I looked around and almost everyone around me was crying as well....
8. Ab Aeterno

9. The Candidate

AS I said before, I'm not counting 'The End'.....