WP as a Windows 8 Companion better than the rest?

I hear a lot about Windows Phone being the best Windows 8 companion and overall Microsoft ecosystem mobile OS. But really - what are the advantages? What can you do with WP that cannot be done with Android?

What comes to my mind:
+Mobile Office on the phone (there is a onenote app for Android though)
+Windows Metro Companion App (at least until now there is no such app for Android in the Windows Store)
+XBox Music (is there confirmation about an Android app?)
+XBox Live certified Games

Do you know more than that? I'm definitely getting a Surface Pro, but am still not 100% sure if I should get a WP or not.