Two specific feeds, /r/popular and /r/all, are a lot of this.

There are a lot of good niche communities that have deep, meaningful conversation on Reddit.

He is clearly unaware of /r/cannedsardines

I've started to add +Reddit in Google searches to obtain useful information when I need to know something. With all those fake top 10 list sites and paid reviews showing up in searches, Reddit is pretty much the only place left for getting reliable product information, for example. There are friendly and knowledgeable subreddits about all kinds of topics.

Yeah. Doing a Google search for best anything returns pages of content farms and Pinterest links. Remember when Google search used to be good?

I'm not sure I understand your taxonomy. In my mind, an image board is a type of forum (generally anonymous and ephemeral). Reddit is more like a forum than a typical forum than popular imageboards, since users have long-lived identities and posts are permanent by default.

As far as "most cat pictures and memes", maybe it is, by volume. But that doesn't diminish the substantial corpus of more substantive, forum-like, discussion hosted on the site.