• mostly post on Lemmy now. So check reddit occasionally as there are a few things there I have need/interest in. I rarely post there now. It's mostly because of their utterly unusable official app - if they allowed third party apps (and my choice of third party app) I'd have been willing to pay to use (I'm not looking for a free ride).
• I'm split between Mastodon, BlueSky, Threads and occasional Twitter. There are people I still interact with on each. I am not a fan of Meta, but unfortunately they seem to be winning. Mastodon is very, very clunky though it has good points. I am seeing an increasing number of big name posters expressing frustration with the platform as there is no good mechanism to ward off spam and abuse at scale - this makes sense (though I certainly am not such a person).
• What's Matrix? I use Discord only because I have to as it's the only place for support/community for certain tools I use. I hate it. I wish orgs would use old school web page support forae like they used to. Vastly better...
• YT premium. Gotta follow the content. I don't mind paying to rid myself of ad interruption, and what's more, it makes it functional for my kids (sans ads). Besides, YouTube Music is pretty good (not nearly as good as Google Play Music was, though).

I think as things scale people may start to appreciate just how hard it is to moderate content to a useful degree. Not too much. Not too little. (I'm not suggesting that any of the main sites has really gotten it right, but when it's gone (at scale) things go bad fast (RIP Twitter).

I hope for better interoperability between platform (fedi) but it's likely a pipe dream.