While the other recommendation in the thread are good, I think they are hard to implement things that will take time.

A quick fix solution can be to add a button on join-lemmy which says something like ‘Confused on where to join? click to join a recommended instance’ that redirects to the sign-up of one of the recommended instances (there is already a list).

This will allow for load balancing and easier time for people to just come and join.