The more professional the context and the more "serious" the requirements, the more attractive Debian becomes. Plus you can make it really free and there are both beginner and expert friendly desktop environments.
I have to install Ubuntu from time to time when the client really insists on it, but it's just terrible. Ubuntu MATE's software boutique recommends Adobe Flash for installation. No joke - it's even the first entry in the "internet" category. This is wrong on so many levels...