To expand a little, part of the reason I prefer 4chan to Reddit is the lack of a content ranking system. This has good and bad results.
On one hand, without user reputations established through upvotes & downvotes, 4chan users can be unhelpful jerks without the threat of ostracism, and their posts will not be made relatively less visible. On the other hand, the circlejerking effect of Reddit disappears, and users are not punished by rank for expressing their precise honest opinion. On Reddit, there is a pressure to recycle vague platitudes that are popular with the community so your post can maintain visibility and your user account can acquire karma.
I am constantly disappointed with the quality of discussion on Reddit, because the most interesting replies are buried if they happen to be on the edges of the Overton Window. Conversations are polite but not particularly rigorous.
To contrast, I recently witnessed a high quality debate on the Labor Theory of Value on /pol/, with a patient and knowledgeable Marxist defending the concept (full disclosure: I am anti-LTV/anti-Marx), and more typical /pol/ users offering rebuttals. There was no ranking advantage for snarky one-liners, and the most thoughtful posts were given attention, regardless of mainstream palatability. Of course, in the same thread someone with equal visibility probably called Marx a faggot.