This is exactly it

Hachyderm is my instance. It’s heavily influenced by techy people, but there’s a bit of everything there. Strong culture of safety for social justice - some of the most followed LGBTQ and Black accounts post from there. I’d highly recommend.

Others I’ve enjoyed browsing are indieweb.social and toot.community

There’s a lot of good info already in here. I’d also recommend checking out the trending post tab, that’s where you’ll typically find some of the posters with the highest number of followers (“hubs” in the Mastodon zeitgeist). I’d also recommend that you follow Lisa Melton https://mastodon.social/@lisamelton. She boosts a ton of stuff and almost single-handedly acts like Mastodon’s algorithm. Her boosts will give you lots of cool accounts to follow, and at the very least will populate your timeline.

Just did, thanks for the recommendation!