Red Hat Linux is one of the more popular distributions. A lot of the other distributions are actually based around Red Hat Linux.

This information was taken from the Linux.org website

Red Hat Linux for Intel, Alpha and SPARC products are built from the exact same source packages. This ensures maximum ease of software portability between machines running Red Hat Linux regardless of the underlying hardware architecture. Your investment in configuration of Red Hat Linux will pay off on all three platforms.

You can find more information at the Red Hat home pages