As a general rule, none of them. Your second condition is going to be a major problem here. Now, there are users on this site of varying spectrums of ideology that are quite capable of debating seriously and civilly with you, but that is not the norm here. Personal attacks and name calling because you expressed the 'wrong' beliefs is as much of a thing here as Reddit, the only difference is you won't get banned. Youll figure out pretty quick which people are worth debating and which are not.

As far as 'subsaidits' go, there isn't much distinction. The vast majority of the users here are just using the whole site like one big sub, since there are fewer users here than most Reddit subs. s/DebateAltRight, s/RealIncels, and s/TumblrInAction, are the only subs with their own userbase that I can think of at the moment, though the same things I said about the rest of the site apply here, perhaps moreso as these are very ideologically based subs, so less diversity in beliefs, and less collegiality towards those who are not in the in-group than the rest of the site

Anyways, if you want to debate you'll find plenty of people willing to argue with you here, just not everyone is going to be worth responding to. I on the other hand, am more than happy to have a good faith debate on a wide range of topics, so feel free to engage me anytime if you'd like to discuss nuanced issues with someone who isn't gonna default to calling you names