Episodes that I can think of right now which I really like is S2 Ep 4, with the Halloween vibe (I love this ep. Always watched it on Halloween as a kid over the years special place in my heart) And S5 Ep 25/26, the idea of having different timelines because of one event really caught me.
I'll be rewatching everything soon though so I might still be updating my current opinion, but those are the ones I could think of right now.
I also remember an episode of Rarity, where her trust was being used by some people in the fashion industry? I cant clearly remember but I love that one too, I cried, it made me very sad, because I love Rarity and she has a good heart.
What about you?