Okay so The Hub had a Top 10 countdown of MLP FiM episodes. I don't have that channel so I am making up my own:

Number 10: Suited for Success

Number 9: Read it and Weep

Number 8: The Cutie Mark Chronicles

Number 7: Friendship is Magic, Part 2

Number 6: Baby Cakes

Number 5: The Return of Harmony, Part 2

Number 4: Winter Wrap Up

Number 3: The Last Roundup

Number 2: The Super Speedy Cider Squeezy 6000

Number 1: Luna Eclipsed