I don’t think it’s especially likely that you’ll find consistently interesting, well-reasoned discussion through any platform bringing together anonymous strangers in an ephemeral manner.
I think consistently interesting discussion has shared stakeholding as a foundational aspect - participants need to actually care, either because the discussion is a product of some commitment they’ve each made (e.g. reading something for a book club), or because the participants are familiar with each other and the outcome tangibly matters (e.g. a physical town hall meeting).
Otherwise, I think you’re more likely to get what you’re looking for from adopting some tangential hobby and having those discussions with the friends you get through that.