Now this one was a little more difficult to choose then the previous ones. Though not that I absolutely loved both episodes as with Bridle Gossip and Sweet and Elite. But these are 2 episodes that I liked but not really among my favorites. Both pretty good episodes, but both seem average compared to my favorites from both seasons.
Now there actually is some similarities between these 2. Both are written by M.A. Larson, Both feature a short scene with Zecora, Both feature the Main 6 in some way, Both have Ponyville get some major Damage, and both threats are ultimately stopped by a particular part of the Main cast (Pinkie in Swarm of the Century, and Rarity in Secret of my Excess). This is one of those ordered episodes that has quite alot of similarities here. And made for some interesting notes while rewatching both.
On Swarm of the Century, I praise it for being another good episode that features the Main 6 each with their own little roles dealing with the main problem of the episode: the Parasprites. Interesting to note is this is one episode that Fluttershy's kindness to Animals turned out making things worse. Something really different then what her kindness have done before. This is also the first case where Twilight goes a little OCD when preparing Ponyville for Celestia's arrival. A precursor to Lesson Zero, especially when Twilight snaps a little near the ending. Which is one of my favorite parts of the episode along with Rarity's reaction when all Pinkie does is grab a flute when it looks like she was going to help. Oh and Celestia's expression when Pinkie's leading the Parasprites out always make me giggle. Speaking of which we know it's Pinkie that solves the problem of leading the parasprites (albeit not cleaning up Ponyville). Albeit a major problem I have with this episode is that while Pinkie does solve the problem, she doesn't just tell any of the Main 6 what she means. And then she complains that the others aren't listening to her. Well maybe they'd listen if you actually said anything? But other then that, it's an enjoyable episode in it's own right.
Secret of my Excess is of course the 2nd Spike centered episode in the series. The previous one being Owl's Well That End's Well. And this episode was pretty good too, it might be my favorite of the Spike episodes. While compared to the previous episode most of the roles are handed to Twilight and Rarity, each of the Main 6 each bring something to this episode Pinkie Pie's cake assault, Fluttershy and Rainbow's "Good Cop, Bad Cop" around Giant!Spike Ear's, and Applejack's "Get my Rope" each brought something to the table. A part of Dragon Quest makes the Doctor and Vet scenes make more sense as there's not even books about Dragons. The existence of Dragon Quest literrally makes this episode better as I think some complaints about it "Why doesn't Twilight search for information on Dragons in her library?" Dragon Quest answered that. Also while they're not too huge deals the references to Godzilla, King Kong, and more were pretty neat to see. And while I'm not a Shipper and the Spike X Rarity stuff wasn't too big. It was cute still, (If you're a Rarity X Spike shipper at all I expect that this episode you'll instantly give the point to) especially the falling scene. This episode also added some mythology to the Dragons in the show. While it actually made more questions then it did Answers (I have a feeling that Dragons in FiM will forever be up to the fandom to decide how they work. Every single Spike episode that people are expecting answers from are just going to make more questions). I think it added a little more depth to this episode.
Tough call, but I'm going to give this one to Secret of my Excess. Swarm had some memorable moments, but I feel like it just doesn't live up to Excess for many reasons. The conflict between Pinkie and the Main 6 holds back that episode quite a bit (Like I said, maybe they would of listened to Pinkie if she said more then "I need a (*insert instrument here*)". And the fact that Secret of my Excess put more discussion about Dragons and the Mythology of the series, especially when it was made better by what happens in Dragon Quest: It's just a more notable episode overall. Basically Dragons > Parasprites, Rarity's (Albeit not intentional) Solution build-up > Pinkie's Solution Build Up. Therefore Secret of my Excess > Swarm of the Century. Point goes to Season 2
Season 1: 4
Season 2: 6