Distribution of nodes and users per platform (according to the-federation.info stats, which started to count all Fediverse networks).
https://socialhome.network/content/1570586/daily-statistics-from-the-federation-g
#Mastodon is in the lead (47.8% nodes / 87.6% users)
#diaspora comes in second (9.9% nodes / 11.1% users)
Numbers are still an approximation.