I'm on SDF for its no-defederation policy and because SDF outside of Lemmy has a proven track record of public service and longevity. Like SDF is much older than I am. Occasionally there are hiccups and the SDF team is a bit slow to respond, but otherwise it's been a good time. And the people here seem pretty chill too.

For my needs it's the best one. But you might want something with a curated feed, a particular political orientation, a smaller or less crowded instance, or something else.