Advantages of XMPP over Webscokets for Android Chat App

I am about to create an Android chat application with image sharing and came across two contenders for its implementation, XMPP and Webscokets. I found some tutorials for creating an Android chat app using Websockets and haven't used anyone for XMPP, although Whatsapp uses XMPP. I'd go with Websockets, but many cite the fact that using websockets will quickly kill your phone battery.

Before getting into one of them, what are the benefits of using either Websockets or XMPP for an Android chat app?