Here is why.
In this picture you can see OpenSuse 10.3 showing the package conflict problem, which need to be handled manually by the end users.
This is OK for technical guys like you and me, but think about normal end user...
On the other hand, I never faced this problem with Debian or Ubuntu. Thanks to debian package format, this kind of issues are almost impossible with deb packages.
Another problem with OpenSuse 10.3 is that, default application which is used to install new application is just awful. Its no way as usable as synaptic. It does not behave as expected, the search function behavior is pathetic.
Come on Novell, what's the problem with you to use synaptic as the default application to install new packages ? That too when there is already a version of synaptic available for rpm. Nevertheless you can install synaptic manually.
So in other words I am back to Ubuntu again. However, I have still kept OpenSuse in hard disk to test it further. If I find something interesting, I will blog about it.
(Thanks to howtoforge.)