IMO...
Reddit tried to find the Boston Bomber, but it ended up being a witch hunt that pinned it on a bunch of incorrect suspects. 4chan would've told the bombers how to improve their explosives.
Yes, 4chan is almost infinitely more vile (and knows it) due to it's anonymous nature, but that's the same reason that it is completely honest with itself. Reddit is the opposite, trying to be perfect in every way. They almost always **** up, and then try to deny it.