The mbin instance with the most users listed there is fedia.io.
The kbin/mbin term for what lemmy calls "communities" is "magazines" (slightly annoying from my standpoint; I'd rather have all instances use a common term for what's functionally the same thing).
Lemmyverse.net separates kbin and lemmy communities in its community index; you need to switch to "kbin magazines" in the hamburger menu in the upper right corner to see them. I don't think that they are presently indexing mbin instances (I mean, they probably have the code to do it if they can index kbin instances, just need to also do the "mbin" string, I guess), because I don't see any magazines on fedia.io listed there. In fact, I don't know if their indexer is working correctly with all versions of kbin, because I see magazines on kbin.cafe, but not kbin.social.
!kbin@kbin.social and !kbinMeta@kbin.social might have sufficient overlap for whatever you're looking for, given that kbin and mbin are pretty much identical software packages.
The biggest Mbin instance is fedia.io. Here are the biggest communities on that instance: https://fedia.io/magazines/threads?query=&fields=names&federation=local&adult=show.
Looks like it's only these two that are actually active
I'm not sure exactly what you mean by "mbin communities".
Like, communities on an mbin instance?
https://mbin.fediverse.observer/list
The mbin instance with the most users listed there is fedia.io.
The kbin/mbin term for what lemmy calls "communities" is "magazines" (slightly annoying from my standpoint; I'd rather have all instances use a common term for what's functionally the same thing).
Here's fedia.io's list of magazines:
https://fedia.io/magazines?query=&fields=names&federation=local&adult=show
The magazine with the most users on fedia.io appears to be !firefox@fedia.io, followed by !fedia@fedia.io.
You mean communities about mbin?
Lemmyverse.net separates kbin and lemmy communities in its community index; you need to switch to "kbin magazines" in the hamburger menu in the upper right corner to see them. I don't think that they are presently indexing mbin instances (I mean, they probably have the code to do it if they can index kbin instances, just need to also do the "mbin" string, I guess), because I don't see any magazines on fedia.io listed there. In fact, I don't know if their indexer is working correctly with all versions of kbin, because I see magazines on kbin.cafe, but not kbin.social.
!kbin@kbin.social and !kbinMeta@kbin.social might have sufficient overlap for whatever you're looking for, given that kbin and mbin are pretty much identical software packages.