My most important consideration is that I need to use an instance which will not block or be blocked by the instances my friends are on - which include without limitation all of mastodon.social, shitposter.club, and pawoo.net. And I have to be able to reasonably expect that that will remain true, and that the instance will remain in operation, for several years at least.
For an instance to really not be involved in the culture war at all shouldn't be a special request, but it seems to be.