A WPF like framework for each platform would be very nice. Code the interface three times and share back end code between them. I also like Xamarin.Forms' way.

A WPF like framework for each platform would be very nice. Code the interface three times and share back end code between them. I also like Xamarin.Forms' way. Describe, in general terms, what you want the interface to look like, and it generates native GUIs for Windows Phone, Android, and iOS that follow each of their different UI conventions (tabs at the top, tabs at the bottom, menu button, etc. depending on the OS).