A quick two penneth (putting the privacy elephant in the room aside for a moment):
Bluesky: first experience - empty. Void. Hard to find people I want to follow.
Threads: very quick easy setup process if you’re on insta (which will be key for most people), but once in its chaos and anxiety inducing. Can’t turn off suggested posts, doesn’t remember where you were (and it’s an algorithmic timeline anyway).
It’s interesting to dip into others, but it just solidifies why I’m on Mastodon.