Bloglines was my RSS reader of choice for almost 4 years. I loved using it because it was web-based, easy to use, fast, dependable, full-featured (in 2004), and free.
Unfortunately Bloglines was ignored for a couple of years by the developers, during which time I stuck with it doggedly anyway. It got slightly less dependable (i.e. the notorious "Bloglines plumber"), and other readers overtook it in terms of functionality. Surprisingly, it was the new beta version which eventually drove me away - it was a case of too little, too late - and worryingly, the beta initially didn't work properly for...