The interface of the Google Reader is just better, and while the Bloglines folks have tried to upgrade their offering recently, giving it some small updates to make incremental improvements - it's like putting the proverbial lipstick on a pig."
Ah! I use the bloglines toolkit constantly for web clipping to Breadcrumbs. It's part of the reason that I seldom think of swapping feed readers. I use Rojo for high-volume, low-information feeds and don't think twice about marking all feeds read. Google Reader doesn't seem near as useful as the above, maybe if I found a few more hotkeys it could be.