Minimal delay between a program releasing new features or bugfixes and you getting to use them. Even as an avid Debian user, sometimes I get bummed out when they freeze a package for release right before a feature I would have really liked makes it in.

As for security, there's not a huge difference I'm aware of. On Debian, features stay where they are, but maintainers will backport just the security fixes of each package to the current stable release.