I'm starting to think Season 4 was the best season too, there were just so many good episodes. My favorite episode right now is either Twilight's Kingdom or Testing Testing. The finale was just an hour of pure awesome and Tirek was one of the best villains we've seen so far. On the other end of the spectrum Testing felt almost like a better animated Season 1 episode, the six girls all together in Ponyville with some problem, a great slice of life episode. My top 5 are;
Twlight's Kingdom Testing Testing Pinkie Pride Trade Ya Sweetie Belle Toils
No the only episode I truly didn't like was Daring Don't. I honestly hate the idea that Daring Do is a real pony, the whole idea makes no sense at all to me and I just plain didn't like it. Another episode that I just didn't like for reasons was Twilight Time, though Twily eating a burger was good to see.