Check out https://piefed.social/auth/instance_chooser

If you go here you can sort by size, uptime, etc, I’m not sure if anyone has made a curated list anywhere. There’s only a few instances with 100+ users, but since you’re seeing all the same fediverse content anyway it doesn’t matter much. My policy was to just pick an instance I trusted (already trusted Blahaj, so that was easy).

I would say it’s probably a good idea to pick an instance with at least 30-40 people, because the more people who have subscribed to remote communities, the more content will automatically federate to the instance (therefor making it easier for you to find new content).

ooh is there a list of piefed instances from most popular to most endorsements?

There's a built-in instance list on piefed when you click on "register". It's sorted by server speed. The most popular must be piefed.social.

And specifically ones that tailor to solarpunk/anarchism/lgbtq+?

In reverse order, piefed.blahaj.zone for a lgbtq+ instance, and anarchist.nexus as well as quokk.au for anarchist ones. @povoq@slrpnk.net mentioned the possibility of a solarpunk piefed instance in the past, but it's yet to become something concrete.

i wonder why everyone shifted to piefed? is it because one of the lemmy devs had a controversial past?

I think it's half because piefed has more features, develops faster than lemmy, and half because the lemmy devs are pricks (one being a transphobe, and the other not being all that bothered by it).

I have an alt on https://quokk.au/, there’s also https://anarchist.nexus/.

People just like it better. You're probably overthinking these things. The point of federation is so that these decisions don't matter as much. (Almost) all the instances are connected and sharing the same community and content. There is no magic "best" place to be, and if there is, it won't be because it's "popular" it will be because it's "the right one for you".