Username or EmailPassword
Easy upgrading when you stick to the package system. What more could one want?
Up to date packages. Debian is just too obsolate.
For server environment, three key products are too obsolate to run anything in production: PHP, Apache and MySQL.
Just my opinion. If we'd move to debian to run our 100 000 lined PHP software - it would be a disaster. i386 "optimized" slow packages and totally obsolate software. Solaris + Self-built server software + high-end Sparc machines are the way to go