I'm a longtime Bloglines fan, but there's a flaw there. Bloglines shares all feeds by default. You can mark a feed as private, but it will still be found by searches. So it's not a good place to put a Backpackit feed that exposes business ideas, for example.
Google Reader is private by default. Only items in the shared folder are public. Users can subscribe to the shared folder, thereby doing secondary syndication. I'm going to try GR for a while.