I have used Redhat for many moons, from around v2 or v3ish. They have always made life interesting with their choices.
Mandrake seem to have the challenge of actually staying in business.
Both of which decided my change to Suse. The best part of suse for me is that you can still get updates via yast (the suse version of RHN) for free on as many systems as you want. No registrations, nothing.
The downside to suse is that they do not release ISOs, you end up with either a network install or buying the product.