There’s a lot of factors to consider, enough factors that there’s no consensus on how you make this choice and at the end of the day you have to pick one and run with it.
A random list of some factors you could potentially consider before yolo’ing:
Is the admin team good? Are they power-tripping jerks? Are they ideologues who are likely to defederate the world for no sensible reason? Do they have a good head for policy? There’s no easy way to evaluate this, you have to look at the sidebar to see who the admins are, stalk their posts a bit, read the modlog for banned users (but he aware that moderation decisions are federated and anonymous so it can be hard to tell what mod did what), and you yourself have to be good enough at these things to recognize quality (or at least alignment with your own values).
Is the instance well-funded and is the admin team prepared to deal with the serious stuff like child-porn reports and subpoenas? Again, this is hard to check for. Basically, if an instance has been pretty big for years (there are only like 2 or 3 Lemmy instances like this and they’re all overloaded) or has the admin team run some other big service before?
Are the instance rules compatible with your topic? Don’t run a porn sub in an instance that bans porn. There are vibe concerns as well, like an edgelord meme community is not going to do well on a hyper-moderated safe-space-oriented instance.
Is the community topic geographically based? You might want to pick an instance homed in that geography. This can be eval’ed by using ip-lookup tools of the instance doesn’t advertise its geography.
Is the instance homed in a jurisdiction that has favorable laws for your topic? It’s better to host a community for sex-work or bourbon on an instance in a jurisdiction where those things are legal, rather than in the UAE.
Is there a topic instance that specializes in your topic? There’s a pathfinder TTRPG instance and a star trek instance, is there one for your topic? Note that topic-based instances can fail some other and more important criteria like being an experienced admin team. It’s possible that a topic instance is NOT the right choice, but it’s worth considering.
Is the server overloaded already? Mebbe pick a different one.
Is there already a well run community on another instance? Help that one grow, don’t splinter the community further.
There are many more factors to consider, and no one considers them all. Eventually you have to pick an instance that’s “good enough” and run with it. But those are some of the major factors one could consider if you’re willing to put in the non-trivial amount of effort required to evaluate them.
There’s a lot here I’d not considered so this is helpful, thanks.
The splintering is an issue I’ve run into already. When I searched for squaredcircle on the assumption the subreddit community had started moving, I got results for five ‘squaredcircle’ communities across five different instances and none of them have a significant membership. I don’t want to further splinter the community by creating another community as you say, so I figured I’d just have to subscribe to all of them and wait to see which one takes off. I guess it’s going to be down to the subreddit mods to say “this is where we’re going”, if that’s even what they want to do. Until then it might be a bit daunting for those making the jump but it is what it is.
The splintering is an issue I’ve run into already. When I searched for squaredcircle on the assumption the subreddit community had started moving, I got results for five ‘squaredcircle’ communities across five different instances and none of them have a significant membership.
Yeah, I blame Lemmy’s fairly terrible cross-instance community discovery and just being young. Reddit had overlapping communities as well (tons of DnD subreddits, tons of aiti subreddits, and there were plenty of high-profile community split events over mod policies). But because it was so well established in recent years… most communities had standardized on one well-run subreddit.
But Lemmy’s community search is so poor, I think folks legit fail to find bigger/better off-instance communities and so no single one gets a toe-hold to gain critical-mass… they all just kind of smoulder with catching fire. Hopefully better community discovery will come and the well-run communities start to rise to the top.
Were you a subreddit mod? In this case my advice would be to contact the existing mods of the lemmy communities / kbin magazines and see if one of them is willing to hand the community over to you (add you as mod, they step down). If so, you've found your new home!
(you may want to re-make your account on the instance that you're primarily spending time on, for convenience, in case federation doesn't work for several hours at a time here and there, etc)
At the same time as keeping an eye out for "power tripping jerks" you want to watch for poorly moderated instances as well. Instances with little to no moderation are at risk of being defederated by other instances if they can't stop their users from trolling/harrassing/evading bans/blocks, etc. You don't want to set yourself up on what seems like a big instance only to have it disconnected from the rest of them because bad actors decided it was a safe haven for acting up.