I don't really see this or Surface competing with each other, they're different classes of devices.
Nexus7:Fire::Surface:iPad. Even then that's a stretch, Surface is more of a laptop replacement, rather than a tablet trying to cover the most common tablet functions.
If you need web browsing, media access, some other utilities and functions the ecosystem provides, you get an Android tablet.
If you want something nicer, and the other functions the Apple ecosystem provides, you get an Apple
If you want something closer to an actual laptop replacement, the Pro Surface is your best option.
If you want just browsing, email, etc... an iPad and Surface are overkill.
If you want something to replace your laptop you're likely going to be pretty disappointed with a Kindle Fire.
I'm not really sure where the Windows RT Surface really fits, it's more of an iPad-level tablet but with an ecosystem in it's infancy... which has it's good (it's Windows) and bad (number of apps, also for some the fact that it's Windows) points.