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.