I knew mastadon was the largest, but I didn't realize how much larger it is. Mastadon is 78% of the fediverse users, while lemmy is third place at 3.3%. Misskey is second place with roughly double lemmy's users. Looks like it's a jp only thing.
I think most of the stats are deceiving. In my opinion, most of the actual activity or users read, and comment happens on Lemmy, as opposed to mastodon where you mostly just have observers. 
You may want to browse microblog tab on /kbin (which shows Mastodon, Misskey, etc. toots/tweets/notes/whatever there) to make an opinion for yourself.
Individual magazines have their own microblog sections (like photography)