Apple's arch rival Samsung will get an early advantage by debuting the most anticipated Android smartphone of 2012 - Galaxy S3 on May 3 at Samsung Unpacked event in London. Apple's sixth generation iPhone, dubbed iPhone 5, is expected to debut later this year, in fall. Which of the smartphones will leave its mark behind?

Samsung has confirmed that Galaxy S3 will pack Exynos 4 Quad chip (1.4 GHz), though a dual-core Qualcomm Snapdragon 4 chip-powered Galaxy S3 could be heading to the U.S. Other specs are just rumors, but if they are to be believed, Galaxy S3 will be an Android powerhouse.

Galaxy S3 rumored specs are impressive to say the least. The device is expected to boast of Super AMOLED 4.8-inch display (some Android watchers claim 4.7-inch), Android 4.0 OS (aka Ice Cream Sandwich), 12-megapixel rear-facing camera, and a curved design with ceramic casing.

A leaked service manual shows traces of a physical button as well as two capacitive buttons on either side.

Connectivity features are expected to include 4G LTe support, Bluetooth, Wi-Fi and NFC.

Samsung is also expected to unveil a new cloud storage service called S-Cloud, which reportedly will take on Apple's iCloud.

As for the iPhone 5, Apple has kept its lips sealed about its specs, but it's definitely going to be the first iPhone that will support 4G LTE network. Speculations are also rife that it will be powered by A6 quad-core processor and will sport a unibody construction using a new alloy called Liquidmetal, that will make iPhone 5 lighter, thinner and more robust and resistant to scratches and dents compared to its predecessors.

iPhone 5 is also expected to boast of a bigger screen size, with some analysts suggesting a 4-inch screen. Some rumors even claimed that Apple will equip iPhone 5 with a 4.6-inch screen.

Rumor mills are also buzzing that iPhone 5 may boast of a 3D camera that will include face and gesture recognition.  The device is also expected to integrate NFC technology as an Apple patent shows iTunes purchases through NFC or e-mail and the ability to share playlists through a "gifting" process.

And, last but not the least, iPhone 5 is expected to break the 8mm thickness mark as Apple could use in-cell touch panel technology that places the phone's touch sensors inside the panel rather than above it. Use of in-cell touch panels on the next generation iPhone could result in thickness savings of 0.44mm. iPhone 4S measures 9.3mm in thickness.

A look at the rumored specs of iPhone 5 gives the impression that Apple is well-prepared to take on Samsung's latest challenge. Rather, though Samsung may have a head-start over Apple is terms of launching the flagship smartphone, a fall debut could actually be a blessing in disguise for Apple as it gives the tech giant enough time to go back to the drawing boards and modify the specs of iPhone 5, if necessary.

Who'll be the winner in this epic smartphone battle? It's too early to tell.  But one thing's certain - 2012 is going to the best ever year for both Android as well as iOS fans.