So far I've only replaced my motorsport subs (mostly F1) with Autosport Forums, a bona-fide old-school and vibrant community to this day.
Years ago I enjoyed the discussion on bluelight.org - happy to know it's still going strong.
What's missing in my life is a forum for movies, TV shows and one for video game discussion. Any suggestion?
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My issue with Reddit is I started using it in my 20s and now 15 years later, the average age is still 20. The quality of discussion is on the floor, though some love to mention subs like /r/askhistorians which are an exception among a sea of memes, one line puns and terrible moderation.