Ooooh! Good question! I'll be following this as well to get some recommendations. :)

It just depends what you are into. Just use the search function and give it a go.

I'm really enjoying /t/millenials because the chief of that tribe is seriously kicking butt posting great links. I'm also enjoying /t/webcomics , /t/howto and /t/musicvideos mostly because I'm finding I'm getting into lots of new things that I hadn't heard of before, which is a pretty awesome experience overall.