What episodes would be best to start with? What storylines would I be totally missing out if I didn't see?
For the most part,
My Little Pony: Friendship is Magic episodes have fairly self-contained story arcs that are not serial in nature, so you should be able to watch nearly any of the episodes and be able to follow what is going on in them without much, if any, difficulty. While it is pretty hard to come up with a short list of MLP:FiM episodes to recommend for any reason due to nearly all of them being great in one way or another, if I was going to recommend four episodes for someone to watch to get started with the series I would have to recommend:
- "Winter Wrap Up" - Not only does this episode have one of the best songs in the entire series, but it also does a great job introducing you the first season's primary protagonist, Twilight Sparkle, and her conflict of being new in Ponyville and wanting to be able to fit in with her new home and friends. Because of this, this episode can be a good setup to the series if you don't have the time or desire to watch the two-parter episodes "Friendship is Magic" parts 1 and 2.
- "Dragonshy" - MLP:FiM episodes have a tendency to come in two primary flavors, which are "adventure" episodes and "slice of life" episodes. "Dragonshy" is an excellent example of one of the better adventure-toned episodes, and involves the Mane 6 making an epic-style journey up a mountain to confront a dragon that is endangering Ponyville.
- "Boast Busters" - This is the episode that ended up finally getting me hooked on the show, and is in my opinion one of the funnier episodes, especially because of Twilight Sparkle's spell #25! The antagonist of this episode, The Great and Powerful Trixie, is also quite the show-stealer!
- "The Best Night Ever" - This episode contains several fantastic MLP:FiM songs, and shows each of the Mane 6 characters' desires and how they try to achieve them. Fluttershy has a hilarious loss of composure in this episode, and Pinkie Pie's attempts to liven up the gala with her song and dance are also absolutely great!
Lastly, since you have mentioned that you have already seen the episodes "Friendship is Magic" parts 1 and 2, I also have to highly recommend that you also find the time to watch the season 2 episode
"Luna Eclipsed." While it's difficult to choose a favorite MLP:FiM episode since there are so many great ones, I think that "Luna Eclipsed" is my favorite episode of the entire series thus far. The reason why I couldn't really recommend this episode in my list of the first four episodes to watch above however is because unlike most MLP:FiM episodes, this episode is fairly referential to earlier MLP:FiM episodes (namely the above mentioned episodes "Friendship is Magic" parts 1 and 2), and as a result you really need to have seen those two episodes first to truly appreciate all of the humor in this one. However, since you have said that you have seen those two episodes already, I definitely recommend that you also check "Luna Eclipsed" out due to the awesome appearance of Princess Luna, the ponies' hilarious costumes, the most endearing appearance of the character "Derpy" in the whole series, some very funny dialog from Spike, and seeing Pinkie Pie dressed up as a candy-gobbling chicken!
Also, if those are not enough compelling reasons to watch this series, then I also recommend that you watch the brony-made YouTube video
"Why My Little Pony: Friendship Is Magic is so good and why you should give it a chance". The video is a rather lengthy 46-minutes long, but it is extremely comprehensive and well done-- so much so that after watching it last week it made me want to start watching the entire MLP:FiM series all over again even though I have already seen every aired episode already, most of them several times over! If you don't want to start watching this series with great enthusiasm after watching that brony's great introductory video to the show on YouTube, then you probably never will!
