The Kindle Fire HDX 8.9 measures 9.09 x 6.22 x 0.31 inches (231 x 158 x 7.8 mm), and the Nexus 10 comes in as the chunkiest at 10.39 x 6.99 x 0.35 inches (263.9 x 177.6 x 8.9 mm). The Kindle Fire HDX 8.9 is actually lighter than the iPad Air, weighing 0.84 lbs, but since it's a few inches smaller, so it's apples to oranges.
The Nexus 10 is the chunker here, tipping the scales at 1.3 lbs. Hit the gym, Nexus!
iPad Air vs Nexus 10 vs Xperia Tablet Z vs Kindle Fire HDX 8.9: operating system
Apple's iPad is in the exclusive iOS club, coming preloaded with iOS 7. If follows the iPhone 5S and iPhone 5C as the third device launched with Jony Ive's new spit shined OS. They don't let the upgrade devices sit at the same lunch table.
The Nexus 10 and the Xperia Tablet Z are both Android devices, but Sony has added a layer of its own software to the Xperia. It brings a lot of media features, including an in-depth equalizer and the ability to use the tablet as TV remote. There's also a bit bloatware.
The Nexus 10 is stock Android, just how the way Google makes it. It'll get the very latest Android updates, right when they're released, in fact it already has Android 4.3, the latest version of Jelly Bean.
You'd hardly know by looking but the Kindle Fire HDX runs Android 4.2.2, but the Fire OS 3.0 UI Amazon put on top hides it well. It also uses Amazon's ecosystem, not Google Play, making it a whole different animal.
iPad Air vs Nexus 10 vs Xperia Tablet Z vs Kindle Fire HDX 8.9: ecosystem
You'll be making all your iPad purchases through Apple's App Store, which is full of apps optimized for the tablet's Retina display. You won't want for music either, with the iTunes Store and the all new iTunes Radio, as well as books and magazines. Of course, everything you buy will locked in Apple's walled garden, which won't be an issue if you've gotten plenty of Cupertino products.
What's more, Apple has made iPhoto, Pages, Garageband and all of iWork are now free, on all iOS and Mac OS X devices.
While Google Play will be your source for apps on the Xperia Tablet Z, it has media stores from Google as well as Sony, although buyers will be better served by Google's Store, which is spread across far more devices. The Nexus 7, the vanilla Android experience, is primarily a Google Play device, but there are third party sellers if you feel the need to shop around.
The Kindle Fire HDX, however, has no Google Play access, despite being Android at heart. It gets everything from Amazon, and while its selection is hardly lacking, you won't be able to access any Google Play purchases you may have.
iPad Air vs Nexus 10 vs Xperia Tablet Z vs Kindle Fire HDX 8.9: connectivity
Apple is claiming to have doubled WiFi speeds on this new iPad Air, thanks to MIMO WiFi with 802.11n support. If this hold true in testing, it could be the biggest improvement the Air offers over its predecessor, the iPad 4.
As is always the case, Apple will be offering a choice of cellular connected or WiFi only iPads from various carriers. In the US, LTE is available, while it's HSPA+ in the UK.
Direct from Sony you can get an unlocked LTE Xperia tablet Z. In the US, it's GSM, so it'll work on AT&T or T-Mobile. Amazon gives US customers a choice between Verizon or AT&T, in the UK it's Vodafone. The Nexus 10 is the odd man out here, with no cellular connection. Surely that'll come in the refresh.
iPad Air vs Nexus 10 vs Xperia Tablet Z vs Kindle Fire HDX 8.9: Processor
The iPad Air is the first tablet with a 64-bit processor. It packs the A7 chip, the same found in the iPhone 5S, which Apple says is eight times faster than its previous processor.
As the only dual-core, the Nexus 10 is showing it's age here. It packs a 1.7 GHz dual-core Cortex-A15. As we've said, a refresh is most certainly coming (the Nexus 7 just got bumped to quad-core), and Android updates direct from Google help the Nexus 10 from bogging down too much.
The Xperia Z has 1.5GHz Qualcomm Snapdragon S4 Pro quad-core processor, and the Fire HDX has a slightly faster 2.2GHz Qualcomm Snapdragon 800 quad-core.
iPad Air vs Nexus 10 vs Xperia Tablet Z vs Kindle Fire HDX 8.9: Price
Apple goodness does not come cheap. For 16GB, 32GB, 64GB and 128GB WiFi versions of the iPad Air, you'll pay $499 (£399, AU$598), $599 (£479, AU$699), $699 (£559, AU$799) and $799 (£639, AU$899). For cellular enabled models it breaks down thusly: $629 (£499, AU$749), $729 (£579, AU$849), $829 (£659, AU$949), $929 (£739, AU$1,049).
The Kindle Fire HDX 8.9 comes in as the cheapest, thanks to "special offers" from Amazon. If you let Amazon display an ad or two on your lock screen, it'll sell you a tablet for about $20 less. Its WiFi only, "special offers" models cost $379 (£329), $429 (£369), $479 (£409) for 16GB, 32GB and 64GB. The LTE versions cost $479.00 (£399) $529 (£439) and $579 (£479)
The Nexus 10 is the next most affordable, with the 16GB and 32GB guys going for $399 (£319) and $499 (£389). Remember, these are WiFi models, no cellular options here. The Xperia Z is $499 (£399) and $599 (£449.00) for 16GB and 32GB WiFi models, $629 (£499.00) for a 16GB LTE version. Sorry for the lack of Australian pricing, it's not always easy to find.