I use Inoreader which is paid and web-based, but has browser plugins. I wouldn’t say I “mostly” look for activity, since time is limited. The Open Thread on slatestarcodex.com is extremely active, I think it gets about 200 comments per day, but I don’t frequently browse it. Slate Star Codex and Less Wrong are the only actual “communities” in my feed reader. The others that are directly or tangentially related are blogs, and most blogs don’t really engender that much discussion.
I use Inoreader which is paid and web-based, but has browser plugins. I wouldn’t say I “mostly” look for activity, since time is limited. The Open Thread on slatestarcodex.com is extremely active, I think it gets about 200 comments per day, but I don’t frequently browse it. Slate Star Codex and Less Wrong are the only actual “communities” in my feed reader. The others that are directly or tangentially related are blogs, and most blogs don’t really engender that much discussion.