The biggest challenge for prospective smartphone owners is choosing which operating system to use. Geeks looking for an open platform are flocking to Google's Android, while those looking for a simple solution that works well with a strong app store enjoy Apple's iOS. Microsoft's Windows Phone platform is also gaining traction thanks to its stunning interface and partnership with Nokia.

New handsets are released all the time, but here are five of the best smartphone options on sale today.

Apple iPhone 4S
Price: From $799
Rating: 4.5/5

The iPhone 4S - despite plenty of underwhelmed criticism online - sold four million units in its opening weekend on sale. With its retina screen, impressive camera features and promising Siri digital assistant, it's easy to see why.

The A5 system on a chip inside the 4S makes everything from browsing the web to playing high-resolution games on the device sing. The new 8MP camera takes truly impressive shots for a smartphone, while plenty of apps allow for powerful photo editing on the phone itself.

The biggest problem with the iPhone 4S is its digital assistant Siri, which doesn't support any mapping or business listing features outside the US. Given it's still in beta, expect that to change in the not too distant future.

Samsung Galaxy Note
Price: $899
Rating: 4/5

A 5.3-inch cross between a smartphone and a tablet, the Galaxy Note stands out from the crowd thanks to its gigantic screen size and integrated stylus.

The unique size of the Note means it's not for everybody. People with smaller digits will struggle to use the device one handed, and although it does slide into a pocket, it's too big for smaller handbags.

The stylus offers some interesting innovations, but tends to lag while taking notes - more so than writing with your finger. The added gesture controls - like being able to take a screenshot by holding the stylus with button depressed - work well.

The screen is gorgeous and the 1.4GHz dual-core processor makes any task perform well. Battery life lasts all day, which is impressive for a device of this size.

Samsung Galaxy Nexus
Price: $0 upfront on a 24-month contract
Rating: 4/5

The Galaxy Nexus from Samsung is Google's flagship handset for the most recent version of the Android operating system, known as “Ice Cream Sandwich”.

Build quality on the Nexus is impressive, polished in all the right places with a satisfyingly solid weight. The curved 4.3-inch AMOLED screen is stunning, feeling comfortable against your face during a phone call. Ice Cream Sandwich is an impressive interface, intuitive to use for even the most novice user.

Unfortunately, the battery life in the Nexus is underwhelming - you'll be lucky to make it through an entire day without a power top up. For a premium phone, that's disappointing.

HTC Velocity 4G
Price: $0 upfront on 24-month contract
Rating: 4/5

Telstra launched Australia's first 4G mobile network in Australian capital cities last year. The first phone to take advantage of 4G speeds is the HTC Velocity 4G.

That extra speed adds a significant amount of bulk to the Velocity, both in thickness and weight - it's not overwhelming, but it is noticeable. Fortunately, the speeds more than make up for it, so long as you are within the limited 4G network area.

4G also has a tendency to drain the battery pretty fast, and getting a full day's usage while using the next generation network is a tough ask.

With a recent update to Ice Cream Sandwich and an improved HTC Sense UI, the Velocity may not offer the latest and greatest specs, but is a solid handset for power users.

Nokia Lumia 800
Price: $699
Rating: 4.5/5

The Lumia 800 is the first Windows Phone to come out of the strategic partnership between Nokia and Microsoft. It was worth the wait.

Where most Windows Phone handsets are cursed with a generic appearance, Nokia's solid polymer body looks amazing, especially the blue or pink variants. Rock-solid construction is only let down by the awkward to open Micro-USB port cover.