After having used numerous different stand-alone RSS readers I'm now a happy user of Bloglines. It is a hosted service that provides a simple two-pane interface to personal RSS subscriptions. Since it is browser-based the user is not bound to a specific machine and operating system. This helps with the typical work machine/home machine dilemma. For migrating users Bloglines supports OPML import.
Following an hosted aggregator approach Bloglines is bandwidth friendly towards blog servers. All Bloglines users share the same feed database. As a blogger you will find the following line in your web server logs:
"Bloglines/1.0 (http://www.bloglines.com; x subs)"
Of course, "x" will be replaced by the number of Bloglines subscribers to your blog.
I really like Bloglines' ease of use. Today, the service is free of advertisements. However, not much is known about the future of Bloglines and how it will evolve. Looking at its creator's past big changes could be in Bloglines' future.