A lot of subreddits that have been said I'll also miss, but for me personally I'll miss the Math based subreddits I used to follow the most. r/badmath was a particular fav. I don't have many "math people" in my friend group so it was nice to have a place to chat about differnet math topics and learn. But hey, I'm sure with time we can expect a lot of those subreddits to find a home elsewhere. Hopefully here. I like it a lot so far!