I sometimes like to peruse Reddit for some well-defined topics - the trick is to find an appropriate subreddit for it. So, for instance, when I want to follow SpaceX news, I'll tune in to /r/spacex, because quite a lot of people there are aerospace engineers (and some are SpaceX employees), so you can expect detailed, up-to-date and to-the-point news.
My general observation is that the more specialized a community is, and the further it is from ego-involving topics (politics, economy, religion), the more civil the discussions are there. So I'd focus on finding many specialized discussion places instead of one general.