r/askscience
r/games
r/comics
r/diy
r/historyporn
r/photoshopbattles
r/listentothis
r/askhistorians
r/depthhub
r/history
r/archlinux
r/howto
r/iwanttolearn
r/foodforthought
r/math
r/learnprogramming
r/oldschoolcool
r/subredditoftheday
r/thebestofamazon
r/humanporn
r/askculinary
r/biology
r/linguistics
r/theoryofreddit
r/chemistry
r/japan
r/truefilm
r/buildapc
r/penmanshipporn
r/engineeringstudents
r/askengineers
r/sketchdaily
r/colorizedhistory
r/picrequests
r/learnmath
r/dailydouble
r/massdrop
r/hiphop101
These are some of the reddits I'm subbed to.
The trick to reddit is to 1) unsubscribe from all of the default subs and 2) subscribe to small to medium discussion/activity based subs. Photoshopbattles has to be one of the best subreddits because it provides entertaining, new, creative content on a daily basis. Askhistorians is also incredibly interesting as it's usually pretty tightly moderated, meaning you won't find much BS in the comments. Find a general topic that interests you (music), then find smaller subreddits of those topics (K-pop, Hip-Hop, Trance...)
The only problem with this is that I think the reddit admins changed it so only a certain amount of subreddits display on your frontpage at a given time (unless you have reddit gold). Sometimes I find myself missing a lot of content because I'm subscribed to hundreds of different subreddits, but there is an easy way around this (as the next button is unreliable and tends to display older links instead of different new ones): In your reddit preferences check the boxes that hide links you upvote/downvote and just vote on everything you see, even if you don't necessarily agree or disagree (or just hide it if you have "moral" problems with that). Every time you refresh the page you'll have new content.