That's a hard choice it would have to be between these:
Twilights kingdom, this was an awesome episode with some great songs and an epic battle scene!
Lesson 0, Great episode because of charter portrays and development!
Party of one, " "
Magical mystery cure, Not a big fan of alicorn Twilight , but the songs where all amazing and some really good character development.
A Canterlot wedding, A great song and the episode which got me into the show!
Flight to the finish, My favourite mlp song in this and scoots is my favourite CMC