I really would not call HN deep. It is just another public discussion site focused on programming. There are much more niche and focused places with higher quality, but they are, well, niche.
Some subreddits can be good, /r/askhistorians /r/askscience .. but I too am curious if they don't rate HN as being relatively deep what they do rate in that category.
Please point out something legitimately wrong with those subreddits instead of just implying they're shitty by association with reddit. There are hard working people contributing great stuff and it just bothers me when people say stuff like this without pointing anything specific out. Just because there are terrible subreddits doesn't mean that all subreddits are terrible :(
If someone recommends me a subreddit, I would check it out. Reddit is not inherently bad. However, you have to understand a lot of us have a negative perception of subreddits, given how many jerks, trolls and bullies participate in them. Even in the good ones there's so much negativity and discourtesy. It's so sad, I personally am afraid to participate most of the time because I admittedly have very thin skin and those kinds of interactions can ruin my day.
AskHistorians is far more anal than HN with regard to maintaining serious discussion; maybe not quite so rule-bound as StackExchange ("delete this question with five answers and 100 upvotes it's off-topic") but strict about being a sourced, on topic, no memes or humour -type of place.
Something Awful is genuinely good these days. There's strong discussion, a lack of insults/whining, and there are a lot of minorities and leftists posting. It's like the forum equivalent of skimmed milk, where the fat in the milk are the analogous "toxic people".