Andy Kelly’s Danny Dyer Bot is a glorious creation. He also made the aforementioned Dark Stock Photos, which I think is actually manually curated by him, so might not class as a bot really.
Trainsbotting, by Parker Higgins, is a lovely little emoji-made train thing that’s cute to have pop up on a timeline.
Jonny Sun’s made a few, like you’ve probably encountered TinyCareBot.
I prefer TinyDotBot though, which regularly produces series of symetrical dot patterns, as kind of a rorschach test but cuter and without someone performing a rorschach test on you.
And a recent one I followed is Kemono English, which just tweets screenshots from Kemono Friends, a selection of 440 from what I can read in the description. They are all Good and Nice because Kemono Friends is Good and Nice.