I'm currently evaluating these two different ways of developing mobile apps, using famo.us vs. Cordova, which is to say plain HTML, CSS, and JS. What would be more sustainable to use in developing a web app?
Edit: Famo.us is deprecated as of 2015 and does not receive active development, so the answer is quite clear.
AFAIK,Famo.us and PhoneGap address different pain points in hybrid app development. Famo.us provides a performant UI framework for your HTML app. Instead of using traditional DOM layout, it uses it's own rendering engine to position UI elements through 3D matrix transforms. PhoneGap on the other hand wraps your HTML app inside a native program which has an embedded HTML viewer plus some plugins for bridging the gap between HTML and native, so that your HTML app would benefit from native features as well. Using Phonegap plugins HTML app can show Native popups, use device services like accelerometer, camera etc and perform operations which otherwise are not possible from an HTML sandbox. You can use PhoneGap to wrap your HTML app irrespective of which UI framework was used to build it; Famo.us, Ionic, JQuery mobile whatever.