Google Reader. Mostly because it's available on any machine I can login to my Google account, so I don't have to worry about synchronising my feeds on multiple machines.

What could be improved? Well, access to protected, private feeds that require authentication would be good. The problem is, of course, that the workarounds for Google Reader to access private feeds (http://lifehacker.com/5432277/access-password+protected-feed... and http://googlesystem.blogspot.com/2008/04/subscribe-to-authen...) kind of worry me.