There used to be the Alexa ranking for websites but it seems to no exist anymore. Elsewhere I only could find for lemmy.world ranking (something like 55000, yay!) but not the actual userbase, and nothing about any other instance (let alone the entire Fediverse).
I’ll admit to mostly checking into Bluesky for a month in January. The user count is much higher but the quality-post count lower … unless you’re into phographs of cats and mushrooms, product-promoters, and political opinions. Forget any quality posts - a 300-character limit (but unlimited photo sizes) and 60-second audio/video limit encourage superficial sheepiality.
Not a desert, but next to one, and the water prices are higher. Probably 1000 lurkers for every liker, let alone comments … unless you’re an ‘name’ into self-promotion. Some names deliver inside info you’ll not see here.
Lemme delivers as much quality as bsky does. But you have to scroll thru more crap there.