I've used openSuse for 3 years - from kde 3.5 -> 4.2 till now. Just got a Sandy Bridge laptop with an i7 and Kubuntu is the only distro that runs acceptable, but as soon as suse 12.1 is out, I'm switching back. there's no comparison in the professionalism of these 2 distros. Maybe it's more a being used to, but everyday I have points that irk me about kubuntu.
The only other distro I would like to try some is Fedora, but there KDE is not the default, so have lower hopes for it being as good as openSuse.