I judge social media sites in terms of their effects on users mental health and their effects on society. Here’s my ranking in order of worst to best:

1. Facebook, because of the way it algorithmically encourages political division and spreads misinformation, and also because it makes you feel worse about your life by comparing yourself to others.
2. Twitter, for the same reasons as Facebook.
3. Instagram, for making users feel shitty about themselves via social comparison. (Especially for making young girls feel bad about their bodies.)
4. YouTube, for spreading conspiracy theories and recommending unhealthy “rabbit hole” type content to kids, like incel stuff.

Tik Tok is probably the least problematic out of the social media platforms IMO, although that might be because it’s still relatively new, so we don’t know how it’s going to end up affecting society yet.