What are other people's impressions of the difference between the cultural vibe in farcaster vs bluesky vs mastodon vs lens?

(I have my own answers but am very curious what other people's answers are)

FC: builders, Ethereum, culturally US-centric (even though not everyone is from there), financially better off 
Lens: more creators, more diverse, one has to actively establish new social graph and engage with it, if not danger of ghost town feeling 
Mastodon: not really active there, more serious 
Bluesky: no account