How do I swap the content of two phones

I have two Samsung Galaxy S3 phones running Android 4.3 (one for me and one for my wife)

I no longer use my phone regularly (I switched to another phone) but I still need it occasionally (for things that only run on Android)

My wife's phone has a broken screen (a big crack on the glass in the middle of the screen, the screen still shows the image and touch and everything else still works)

I want to swap everything between phones so that my wife has the intact phone (with everything she now has on the broken phone) and I use the broken phone.

So, what is the easiest way to swap the entire content of two phones?