Choose SimplePie if: You want greater control over configuration and settings, you want the feeds you add to your pages to improve your SEO, or you want to ensure your feeds are displayed regardless of the user’s web browser.

Choose SimplePie Live! if: You want to get started using feeds with the least amount of configuration possible, you want to build cool AJAX-style widgets and tools, or you’re wanting to add feeds to a site or application built in a non-PHP environment.

Choose SimpleReader Mobile if: You’re not trying to add feeds to anything, and you have a Blackberry, Palm, PSP, Mobile Phone, Windows Mobile or other web-enabled mobile device that you want to use to catch-up on the latest headlines whenever you’re on the go — in the car, on the train, or at the beach!