To be fair against mastodon the “mastodonservers.net” (first result on DuckDuckGo when looking up “mastodon instance list”) does list an instance featuring primarily pornographic content first (as far as I can tell this is because it list by usercount in decending order), which could be off putting to some people.

The first Google result for the same query “instances.social” is a list, but in the non legacy non advanced view has almost completely non-functional filters.

Neither of these are “joinmastodon.org” which is probably the best website for someone trying to join mastodon, considering it appears to be ran by the developers.