It has quite a reputation from back in the day, but I find Something Awful to have a very high level of dialogue, probably because you have to pay a small fee for membership, and they aren't afraid to probate/ban people.
They have financial incentive to ban at the slightest provocation, restricting everything to safe and predictable "high-level dialogue" that can't challenge the status quo.
Reddit thrives on multiple levels of "dialogue" segregated into their own communities. Its pro-growth vs SA pro-elitist stance. Thats why SA will never be a reddit alternative.