Linux is Linux is Linux is www.kernel.org.. Almost all of the distro's are stable. It is a matter of personal preference. For me, I like slackware, however, if you want to run cPanel and use RPMs you need RedHat Enterprise, Debian, SuSE, Fedora or Mandrake. Out of them, I would go with RedHat Enterprise or Mandrake.
I also suggest running the 2.6.x kernel as it allows for some speed enhancements and it is very stable. Unfortunately, RedHat comes packet with a 2.4.x a kernel and requires a bit of work to get 2.6.x working, however, mandrake comes packed with 2.6.x