oulipo.social: mostly quirky, with interludes of serious posting within the constraint of not using "e"

mastodon.xyz: very large instance. Local timeline is very twitterlike: short toots, not many rants. Lots of French, lots of linux.

witches.town: lots of French, gender quirks, playful. Few men. It's like the good parts of queer twitter, but with added witchiness.