Pair A Tablet W/ Your Android Device - iPad 3 or Surface?

Today I had an interesting discussion about mixed ecosystems and not being attached to one. I currently have a Galaxy Nexus and I'm thinking about switching to a Lumia 920 or upgrading to the next Nexus. I am also planning on buying a Surface but I wanted to hear others opinions.

Which tablet (and ecosystem) would you pair your Android device with? Which do you think meshes better with Android?

For this question ignore any desktops, laptops, etc you have. I have an Ultrabook but I'm ignoring that as well. Just think about the tablet and phone combination.