QT is in every way a better choice, except for the license. Kivy is great, fun to use, but it suffers for the same thing that many python applications do: pack

QT is in every way a better choice, except for the license. Kivy is great, fun to use, but it suffers for the same thing that many python applications do: package management is a pain, packing is difficult (especially dependencies with c libraries), applications are slow, there are no threads (any action locks the UI), the bridge to native code is quite troublesome (especially on IOS), it uses a custom DSL for UI layout and the 'non native' widgets can be clunky. Don't get me wrong; it's a fun platform, but really have a good play with it before you decide to use it for anything serious, especially for mobile targets. (QT isn't perfect either; but its a rock solid platform for building real applications in. Ultimately though, you should really suck it up and write native UI for each platform and only share underlying application logic; if you don't you're just going down the road of various different levels of clunkiness on every platform).