I use Debian because it has stayed true to its principles and because its principles are sound. If innovation is what Ubuntu is after, let them contribute their innovation to Debian or upstream projects like the kernel or GNU or Gnome or XFCE or so many others. They want to be become RedHat alternative? Let them contribute to Fedora. They want to make money? We already have Apples and Microsofts and those have plenty of fans.
I haven't found a single advantage of using Ubuntu or Linux Mint over Debian but plenty of issues instead. Their most visible recent "innovation" Unity with its Amazon and other search results and privacy holes made me realize even more just how valuable Debian is. Their shift in release support makes something fairly useless even more useless. Fedora does a decent job if one wants to reinstall their system periodically and stay on the bleeding edge. Arch or Testing/Experimental do an even better job if one wants to be on the bleeding edge.
Debian just works! Once configured this system delivers day after day after day. I wish I had enough time to devote a good chunk to maintaining, testing, and improving Debian. Unfortunately, for now I can just add to it by using it and talking about it with friends and colleagues.
Xubuntu does a nice job with themes so does Linux Mint but why don't they just try to add their themes to Debian instead? Debian has plenty of room for anyone to contribute. If you have cycles and feel that you can improve something, please consider contributing to Debian - Ubuntu will get it for free and so will Linux Mint. You'll have improved many distributions and not just the one that seems to switch principles every few months.