I was fairly active on Reddit for a while, but I had pretty much stopped using it for anything but a few pretty niche subreddits the last 3-4 years. I prefer the BBS/forum format a lot better, especially since they're generally dedicated to a specific topic. A lot easier to compartmentalize that way.

I started using SN primarily because of the higher rate of well thought out content available. I don't feel I have the knowledge or ability to produce that content myself, but I'm always interested to learn more about a lot of the different topics represented here.