Having tried all three, its a stark difference in how much more social Lemmy is comparatively. Its not even close. Almost all posts I've encountered on lemmy have interaction; whereas, more often than not, posts on the other two platforms have no interaction. Wonder what the driving factor is behind this difference?
Hey, I don't come into your house and insult you by calling you social media! /s
I think, much like HN or early web forums, we're below the population level where personal attacks get unmanageable. On Reddit voicing a dissenting opinion would always get you dog piled and that makes people defensive and boring as shit.
People here are generally (some exceptions being pro life/choice which is a deeply toxic topic at this point and Gaza which has emotions extremely high) arguing in good faith and even if they're rough initially a lot of times I've appreciated back and forth threads since, even if there's still a disagreement, most people will genuinely work to remove stupid misunderstandings and try and understand who they're talking to.
Additionally, the mods on most communities are awesome and focus specifically on removing things like personal attacks without getting heavy handed in interventions.