I've never heard of Kivy before, but judging purely from the gallery on that page, my first impression is that I see no screenshots of any native-looking desktop apps. Unless that's just an omission in the gallery, that would be a good reason to use Qt.
Here is my reason for Qt. Qt won the Linux tool kit wars (My opinion) and it is used by so many projects that it keeps the ecosystem more standardized. Plus when I am at work on my one Windows box I like seeing Qt on there also.
There's LGPL PySide (http://qt-project.org/wiki/PySide) which should be suitable for commercial projects under LGPL, but PySide is Qt4 only. There is also PyQt (http://www.riverbankcomputing.co.uk/software/pyqt/license) with Qt5 support, but its free license is GPL-only, so if you're not doing open source, it's not going to work, unless you buy their commercial license.
BTW, Zeal's original author here - thanks for mentioning Zeal and good luck with your project!
As some personal advice, I wouldn't try Kivy for such content-oriented desktop app. I've tried briefly using it once for doing a very simple application, but it seemed much harder to implement usual desktop-like widgets. Overall it looks like it's good for graphics-rich and custom-rendered applications.
