There isn't one that's going to do everything that reddit does, honestly. You might want to consider breaking down everything you were getting out of reddit that you aren't anymore and pursuing ways to find those things again.

I recently realized that I was spending way too much time on Reddit, so I started only briefly scrolling through Reddit once per day without reading comments, and relying more on HN, twitter, and a few blogs for news. To feed that itch to belong to a community, I started commenting on HN more, and continue to go on JQBX and belong to a few slack channels.