I’ll start.
In my opinion, the best song has to be This Day Aria, I mean wow, I never expected them to write such a great villain song that could rival villain songs from Disney movies.
Another song I find myself putting on repeat is Light of Your Cutie Mark, mostly because of the great harmonies of the CMC starting at 1:11, I get goosebumps every time.
How could you miss Winter Wrap Up when it’s the best song in the series? It had the best remixes and fan content, and it’s the one that gets stuck in my head every single time I hear it.
Winter Wrap Up definetly helped the explosion of fan made content!
This Day Aria is definitely what got me paying attention to the music in the shiw. My absolute favorite still might be The Art of the Dress though. Early season music just hits different
It’s a tie between The Galloping Galla (because Into The Woods is a brilliant musical) and A Little Glass of Water Please (because it’s peak discord).
That song was inspired by a musical? I didn’t even know that.
I think there’s a few early songs that pay homage to musicals.
a full version of the musical if you’re interested
Edit, another obvious musical one is the Flim Flam Brothers Cider machine song