Google Android is now the fastest-growing mobile platform, but Microsoft’s Windows Phone 7 is a compelling rival. Which kind of smartphone should you pick? We consider the pros and cons and help you choose the right smartphone for your needs.

Back in 2008, Nokia declared that the smartphone was today's computer. While that claim may have stretched the imagination, even back then it wasn't a huge overstatement. Processing power is now up to 1GHz with the nVidia Tegra 2 chip, while quad-core processing, 3D video gaming and the ability to output a whole Blu-ray movie stored on a microSD card and show it on a vast silver screen are all mooted.

The Motorola Atrix 4G handset that recently went on sale in the US has 16GB of internal memory and can take another 32GB via a microSD card. Remember when laptops first began touting gigabytes of storage? It's only about five years since dual-core computing arrived too, yet smartphones already have dual- and even quad-core chips.

Features such as HD video-out and real-time 3D processing and output were showcased at Mobile World Congress in Barcelona in February, too.

While all this rich multimedia is staggeringly impressive, for the most part it's not the primary reason why you might choose a particular device in the first place. Most of us would sooner have a dependable phone that allows us to make clear calls, easily access our contacts and call, text or email them, than plump for a really fancy gadget on which calling and connectivity take a back seat.

Similarly, an impressively large or bright screen may not be the best choice if you're unlikely to be able to give your smartphone daily mains-power sustenance. These multimedia showcases require an awful lot of power, despite what smartphone chip makers say. And while you may occasionally want to kick back and catch up on the latest episode of 'Spooks' on the Android version of the BBC iPlayer, that shiny 4in touchscreen needs powering every moment that the device is switched on and in active use, even if you're just having a chat via text or jotting down a note for later.

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Smartphone hardware requirements

In general, a 600MHz or faster processor, expandable storage, a capacitive touchscreen - with or without a separate slide-out keypad - and 512MB of RAM will be your basic hardware requirements. A 3.5in screen with a WVGA resolution of 800x480 pixels should suffice. Check the actual pixel resolution rather than the screen size - VGA resolution on a large 3.8in-plus display will not be crisp, and may look blocky. It's worth visiting your local phone shop and comparing screen for screen – there's a big variation in quality.

A touchscreen with a zoom in/out onscreen slider is a given, but multitouch gives you more navigation control - and will drain the battery faster, too. If you're torn between two similar handsets, the one with the higher mAh battery rating will usually provide more power, so should last longer. However, some smartphone makers do a better job than others of battery management. On Android phones the device settings can be adjusted as you please.

Look for 802.11n Wi-Fi; 3G is useful only if you live in an area where there's solid coverage - consult maps for your area at the respective network operator's website. There are also now defined data-usage limits in place for most 3G contracts, so be mindful of this when choosing your contract and deciding whether 3G is for you.

Most Android 2.1 phones come with 5Mp cameras or better, and some can take better video than others. A VGA-resolution video mode is fine for conducting web chats, but it won't bear muster on even a laptop screen. If you're likely to want to do more than watch your footage on your smartphone or in a browser window on YouTube, choose a handset that offers 720p (HD) video capture. Some offer 1080p (full-HD) video, but this remains a luxury feature.

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Which smartphone platform?

Over the past 18 months, there's been a lot of jostling for position in the smartphone market. The iPhone is the single standout device, but BlackBerry smartphones now account for the largest slice of the UK pie (just), while Android handsets outstrip both for worldwide take-up.

The fastest-growing sector of the smartphone market, Android offers a broad choice of handsets to suit every pocket. Its runaway success has meant innovation and performance updates are delivered thick and fast. Users of every smartphone since the 'Eclair' version of Android that launched in early 2010 have been able to upgrade the OS, but there are plenty of Eclair models that have yet to be officially upgraded. A case in point is the Motorola Defy, which went on sale in the UK shortly before Christmas. Its upgrade to Android 2.2 'Froyo' is imminent, but UK users will have to wait a few more weeks until it's pushed out to their phones.

The Froyo platform allows the phone to run faster and slicker, and has better battery management. It also supports internet tethering. Similar performance improvements are promised with 2.3 'Gingerbread'. However, as yet, Android 2.3 is available only on the Google Nexus S.

Google isn't having things all its own way with Android, however. Microsoft made its big pitch for smartphone notoriety in late 2010 when it announced its revamped mobile operating system (OS): Windows Phone 7. Previously a contender only in the business arena, where security and integration with Exchange servers and Office applications take precedence over design and desirability, with Windows Phone 7 Microsoft has made significant advances. Allied to fun functions such as the Zune media server, and with support for Xbox Live (and your own Xbox avatar), it's a much more tempting proposition than previous Microsoft attempts at a mobile OS.

However, both the Microsoft and Google platforms allow for a lot of mobile operator and manufacturer customisation, and this isn't always a good thing. Smartphone makers and network operators often can't resist stamping their own identity on the handsets they offer, which can cause complications when the user wants to update their device, or conflicts with the handset's own navigation.