All things modern.
This is not an easy question to answer and by the time you read this the answer would have probably changed. This industry is changing so rapidly these days that 3 months ago my answer would have been totally different but today is the first of December 2012 and this is my answer.
There are so many different versions of Android and WP kicking around that the first objective is to narrow down the devices for comparison. As a heavy phone user, I will choose the Nexus 4 (N4) for Android and the Nokia Lumia 920 (L920) in the W8 corner. I have chosen the N4 because although it may not be the highest spec device on the market, it is the only one that uses stock Android which in my opinion is the most usable/stable/speedy version and it is the only one that is guaranteed updates for as long as the hardware will support it. The L920 was chosen because it is the highest spec WP device at the moment, is the one that Microsoft is pushing as the flagship WP device and is available now.
In terms of raw performance speed both handsets are equally speedy. This is not to say that they are both perfect, but they both zip through the interface most of the time and only occasionally sticking from time to time. All mobile devices do this, even my iPhone froze from time to time, and is a consequence not only of the fast development cycle but also the impossibility to test every conceivable scenario given the number of applications available for each platform.
Both devices have 8MP cameras and for the first time a WP can take 1080p video. The camera of the L920 however incorporates optical image stabilisation making it possible to take stabilised video as well as more blur-free stills for those with shaky hands.
Both devices have HD displays meaning lots of real estate for web browsing and watching high quality video. But which device makes better use of the screen real estate? On the home screen for example, the widget system of Android gives the user more control over optimising the screen space than WP’s minimalist tiles. Much of the tile space on WP seems to be wasted blank space. This brings me to the other advantage of the Android home screen; that the user could download and place on his home screen any widget from a plethora of available widgets on Google play. With WP, you are stuck with either the stock WP tiles or those provided by installed applications. Even if more tiles eventually become available, the user is still limited to three sizes. A good example of this is the calendar tile/widget. In WP, even at the largest tile setting, the user can only visualise the next appointment. On Android however, the stock calendar widget is resizable in all dimensions, enabling you have a tall portrait mode displaying the next three or four appointments.
The story is the same with email, the Android implementation simply blows the WP8 version away:
Email on Android home screen.
Email on WP8 homescreen.
Battery life is much harder to judge as this will depend on how heavily the phone is used. Heavy users like myself should not expect to see a huge difference between either device and should both require charging at least every night.
If you are into having lots of media on your mobile device then the L920 is available with more built in memory. Neither has expandable memory and why should they as they can make much more money out of the customer by charging an extra £100 for 16GB of storage space built in. In my opinion however, if you do play a lot of media on your device so much so that storage space is an issue, then you should not be considering either of these phones, the iPhone 5 is for you and I am not being funny. The iPhone gives a much better media experience than WP or Android can ever hope for.
Speaking of media, there is one thing that is stunningly lacking in WP still and in fact is the main reason that I will not be buying a WP8 device. Expectations of what a phone should and should not be able to do change over time. In 2012 I do indeed expect a mobile phone to be able to play video in the browser. If this is too much to ask then it should at least open in a media player window. I am not talking about dodgy porno sites here, I am talking about www.bbc.co.uk. My last generation Galaxy Nexus plays video just fine but trying that on the just released L920 simply shows a message about flash not being installed. This is not acceptable.
I have already spoken a bit about the user interface when comparing the use of screen real estate but there are other aspects to consider. Once the user moves away from the home screen, WP has the usability advantage. Starting an application for example is much easier on a WP because of the alphabetical scrollable list. This is more efficient because humans are naturally better at picking from a vertical list than from a sideways stream. Clearly MS have considered their human factors here. To make things easier if you have a large number of applications installed, you can quickly find applications starting only with the first letter in the name of the application. Android’s system on the other hand copies the now age old iPhone system fondly known as the ‘big mass of apps’ system requiring the user to hunt for what is needed.
WP also has an edge when it comes to application usability. This is because WP applications stick to strict guidelines for the user interface. When all application look alike, they all become easier to use. The user can quickly adapt to where buttons would be, decreasing the time needed to find them. Android by comparison is quite a mess. Applications don’t have any UI rules to follow and as a consequence they all look different and therefore requires the user to learn a new system for each application. Even the stock applications are different with the menu button at one moment being in the bottom right corner and in the next application the top right corner. Even rotating the screen from portrait to landscape can move buttons around drastically within the same application.
The nexus line of mobile devices is more than just a consumer phone, it is the reference device which developers use to test applications. For this reason it is in Google’s best interest to keep them stuffed with the latest updates, and they do. With a nexus device you can expect several updates a year each bringing actual usability and capability improvements. The story about WP updates on the other hand is a disaster. One recalls the bricked Samsungs as a result of MS’s first update to WP7. After that debacle updates were slow and painful with half a year needed to get copy and paste and another year for multitasking. The situation doesn’t seem to have improved either with absolutely no mention of the WP7.8 upgrade for older devices. Some would say that updating your old phone should never be an obligation, you should be happy with the phone as you have bought it. True, but when the competition is doing it, it does not look good and is a sure recipe for losing customers.
There is no question about who wins of price. The N4 can be had for £269 when it is available but a sim-free L920 will set you back £450. For phones that are so closely matched on performance and overall usability, the decision is unfortunately made crystal clear. The L920 is a nice phone, but simply does not have enough going for it to justify the price difference, even if you are particularly interested in the bits it does well such as the excellent camera.
Overall, I would go for the N4 because of its high specification, capability and promise of updates. Remember, today is the 1st of December 2012.