Interesting about people getting banned. I haven't browsed either for a while. More diverse within leftist politics, but across the political spectrum?
I don't think a forum full of edgy memes is a great place for political discussion, /pol/ or /leftypol/
The memes are "banter" and fun, which a lot of people really do enjoy. It's like a bar, where you have most people talking about banalities, but there are a few people who will explain theory to you, link you to books, debate you etc.
Generally a thread is either a meme thread (with small discussion if any) or a serious thread with discussion.