Watches are no longer just simple timepieces and 2013 is shaping up to be the year of the smart watch with increasingly more exciting models set to make a plunge.

Picking just one product and labeling it as the best smartwatch available on the market is quite a difficult task, as plenty of options are now available and each one holds its own. In the end, it comes down to personal preference and the features and functionality desired by each individual.

Some want a smart watch to track their sleep, others want it to track their workouts, while others may just want it as an extension of their phone to answer calls. Bottom line - smart watches now do far more than just display the time and the market is no short of options, so here are the top five contenders.

1. I'm Watch 

The I'm Watch smart watch may sport one of the coolest designs out there, sporting a touchscreen that allows users to drag, swipe, or pinch through the gadget's interface. The device syncs with iPhones and Android smartphones, serving as an extension of one's handset and allowing users to answer calls with a button on the watch.

Moreover, the I'm Watch allows users to receive text messages, e-mails, notifications, or see calendar, pictures, weather apps, or listen to music. The device sports a 1.55-inch, 240 x 240 color display, and packs 4GB of built-in storage. Under the hood, the I'm Watch packs a 450MHz Atom 9 processor and 128MB of RAM. The device comes with a $349 price tag.

2. Cookoo Watch 

The Cookoo Watch is suitable for those looking for a more basic smart watch. The gadget has a digital face of an analog watch, but when it comes to functionality it's quite limited compared to other smart watches. The Cookoo Watch syncs with iPhones and iPads to provide updates and also allows users to check into Facebook or other such social-networking sites. It is waterproof up to 50 meters (164 ft.) and its disposable battery should last for a year. This basic smart watch sports a $130 price tag, and it will soon work with Android devices as well.

3. Martian Smartwatch

"[Martian has] taken the 'SmartWatch' to the next level by adding hands-free voice communication," the company touts on its Web site. "Use your Martian Watch to talk, listen, initiate voice commands, and be notified by incoming calls and texts, all without your phone leaving your pocket, purse or backpack!"

The Martian SmartWatch connects to either an iPhone or an Android handset via Bluetooth, and with iPhone 5 or 4S it also allows users to talk to Siri through the watch. With iPhone 4 and 3GS, users can access the integrated voice controls.

In terms of design, the Martian SmartWatch features a traditional analog face, sporting a tiny screen at the bottom of the device where users can see who is calling. The same tiny screen also gives a 40-character preview of text messages. It comes in three versions, ranging in price from $249 to $299.

4. Pebble Smart Watch 

Pebble can do virtually everything one could want from a smart watch, from keeping track of workouts to socializing on Facebook. The device raised more than $10 million via a Kickstarter campaign, and it officially launched at this year's International CES.

According to the company, the Pebble smartwatch is "definitely customizable," which means that users can download various watch faces, as well as a wide range of apps to maximize the watch's functionality. Pebble can act as a fitness tracker, using the connected phone's GPS to display speed, pace, distance, and other such data, or it can serve as a music player via a music control app that allows users to play, pause, or skip tracks. These are just two examples, but the watch is capable of more.

The Pebble smartwatch sports a 1.26-inch screen with e-paper technology, allowing it to be clearly visible even in bright sunlight. It connects to an iPhone or Android phone via Bluetooth and allows users to check text messages, e-mails, as well as social networking sites such as Facebook and Twitter. Its rechargeable battery should last for a week on a single charge, and the device is also water resistant.

Pebble will start shipping to Kickstarter backers from Jan. 23, and it will later be available to the broader public for $150. It comes in a range of colors, including red, orange, gray, and the classic white and black.

5. Basis Science 

The Basis Science Smartwatch is designed to help users with their workouts. This wearable fitness companion is similar to FitBit and Nike's Fuelband, and it tracks the user's workouts measuring various biometric data in real time. Its sensors can measure heart rate, skin temperature, sleep patterns, and other such things. The device can even measure how much the user sweats during a workout.

The device does not currently sync directly to an iOS or Android app, but the company said it's only a matter of time. For now, a Web interface helps users view and manipulate the data. The Basis Science Smartwatch comes with a $199 price tag.