Reddit is the only one I use nowadays, it has its downsides especially when you look at the most popular feed but in smaller communities it's really good. Also it's the most text-based major social network, which is a major plus for me, as I find written content to be usually more in depth and therefore more interesting (and, for me, easier to "absorb") than videos or pictures. I also have a Twitter account but I don't really like to use it, the main problem I have is that I follow a few people mostly for niche interests (plus a few news pages), but due to how Twitter works you always get anything they tweet or retweet no matter the topic - and imho it easily gets annoying to have to skim through dozens of tweets just to find a single interesting one.
I used to be on Facebook but left it some time ago mainly due to ethical concerns with the amount of tracking that Facebook does (meanwhile I've never really used Instagram, I had an account many years ago but I was never interested in how it works).
I've been thinking of joining a federated network (Diaspora or Friendlica, given their focus) for quite a while but I'm not really much of a social media person anyway so I haven't joined any yet.
