Looks like KBin has an edge over Lemmy now in terms of monthly active users.
It's obviously a pretty silly thing, and is not in any way indicative of which project is "better" or more "long-term viable" or anything — instances of both federate with one another, and with the rest of fedi, so it's all one happy family.
That said, it's notable. KBin is a relative newcomer to the "Reddit-like fedi instance" game, and also does not have the tankie baggage.
Anyway, the more, the merrier!
KBin: https://the-federation.info/platform/184
Lemmy: https://the-federation.info/platform/73
Discussion on fedi: https://mstdn.social/@rysiek/110527049024028986
Looking at my own very small instance, Lemmy doesn't seem to consider "logged in" as active. I currently have 8 users online and 3 users/month.