I want to avoid circle jerks, nonsensical news items and conspiracies, etc. /r/politics and /r/The_Donald both offer no value to Reddit or society, they are all just echo chambers, and they don't value or encourage diversity in view points. They are the same thing but on opposite ends of the spectrum. /r/Politics will be full of "ShareBlue" links and /r/The_Donald will be full of Breitbart. Not sure where the diversity of thought comes into play, which seems to miss the point of a "forum."
Anyhow, on the Facebook front you have equally uninformed people telling you their opinion on something, usually based on a false premise from a biased source they read...except this time you actually -know- these people.
If you do try to find a middle ground, which is generally where most truth is, in the grey, you are attacked by both sides for not being on their team. Like it's some game.