In terms of politics discussion there sadly isn't much better than this forum, and believe me I've looked.
politicalforum.com is good, but too dry, slow moving and pretentious.
Debate Politics Forums is more detailed, but people are incredibly
entrenched in their positions and it's more about "how can I make this event pro-my side" like they are all talking heads on Crossfire instead of cognoscenti discussing the world.
predictit.org used to be good (like intrade was) and have the absolute latest information, but now the site is all memes and pumping. Nobody tries to use group think to hone in on truth, 80% of what you see is jokes or misguidance or joking misguidance.
What this community mostly suffers from is the lack of good opposition, and there's a huge barrier if you're opposition. During 2008-2012 Obama years we had no credible right wing people. Now we don't have any credible left wing people, and most of the liberals are pro-Trump. The anti-Trump people are not only budget-class posters, but are barraged by all kinds of venom when they arrive. It's difficult to say, "I don't like Trump" here without demands for you to defend everything HRC has ever done.
We'll have posters that are fairly smart and anti-Trump, but they aren't well versed to the issues and bring up misconceptions that have been annihilated multiple times, then get BTFO and lose the motivation to stay in the ring and keep arguing once they learn the ropes.
However, unlike a lot of pro-Trump communities, you have a lot of people that don't really buy the hype behind Trump while still liking him, and are fairly critical of a lot of moves he makes while still overall looking forward to what he does.