The website is moderately usable but an independent app called Apollo really makes it a pleasant experience on my iOS devices. Hoping for a macOS port sometime.
Edit to add some specific communities:
/r/GunDeals is one of my favorites, but is incredibly dangerous to my wallet.
/r/CCW is a great resource for concealed carriers.
I know it's childish, but the various meme subreddits can be hilarious at times. I like /r/historymemes /r/grimdank (warhammer memes) and /r/lotrmemes among others.
I also keep subscribed to /r/Clojure and others but I get most of my professional news from HN.
/r/DestinyTheGame and /r/DestinyLore are fun but the former can get a little salty when things in game are changed.