Honestly, the one with best moderators that put effort into building and maintaining a community rather than letting it sit there. Building a space like this isn’t really luck as much as hard work. Take a look at [email protected] for example, they are promoting the community on the subreddit and being (pro)active on their instance, and it’s working. If we make it a nice place to be people will come, but it rarely happens on its own (especially with reddit looming over as established competition).