The cost of memory is coming down drastically, thanks much in part to the fact that manufacturers are cramming more capacity into thinner and thinner hard drives. Today, it’s not infeasible to get a 1 TB (that’s about 1,000 GB) hard drive for less than $200. An external hard drive is a great way to back up your important data, save your photos and videos and take your media libraries on the go. They are portable, reliable and easy to install. But which one is best? Here’s my take:

Iomega Professional Hard Drive 1 TB - $99

After considering memory capacity and price, the next most important aspect to scrutinize is performance. The Iomega Professional Hard Drive scores high in all departments. At less than $100, you won’t find a cheaper price per MB than this one, and because it’s both an eSata and USB 2.0 hard drive, you can transfer files much faster than with USB alone. The eSata interface lets you transfer at 6x the speed of USB 2.0 or FireWire 400, while the USB 2.0 lets you connect to laptops and other computers that may not have available eSata ports. Weighing just 2.8 pounds and measuring 4.4 x 6.1 x 8.9 inches, this hard drive is unobtrusive in a laptop bag or on a computer desk.

Seagate FreeAgent Go Portable External Hard Drive – 640 GB - $199.88

While not as ample as the Iomega Professional Hard Drive, the Seagate FreeAgent Go Portable External Hard Drive makes up for its smaller stature with its portability. This hard drive weighs only 5.6 ounces and measures up at 0.5 x 3.2 x 5.1 inches. Plus, it’s powered completely by the USB port, meaning you don’t have to plug it into a wall. With 5400 RPM and an 8 MB cache, it’s surprisingly well performing for a portable hard drive as well.

Iomega eGo BlackBelt 500 GB USB 2.0 Portable External Hard Drive - $101.99

If you are prone to dropping things—such as your portable hard drive—the Iomega eGo BlackBelt is a good investment for you. This ruggedized portable hard drive features a shock-resistant black belt of rubber around its sturdy external casing that absorbs shock to protect your precious data. Rated to withstand drops of up to 7 feet, this hard drive won’t quit on you, even if it takes a few dings.

LaCie Hard Disk Quadra External Hard Drive 2 TB - $192.68

On the other end of the spectrum is the LaCie Hard Disk Quadra. A dense, immoveable tank, this beast has 2 TB of storage and features a USB 2.0, FireWire 800 and eSata port for maximum speed. The FireWire ports lets you connect a camera or another device to it directly, so you don’t need to fire up your computer just to back up your home videos. At a hefty 3 pounds, this hard drive is certainly not meant for portability. But if capacity and speed are your priority, the this is an excellent buy.