Which 3 TB Hard Drive Is Best?
Given the different priorities of all four drives, it would be both unfair and unnecessary to choose a single winner.
If you put the highest importance on low power consumption and quiet operation, the energy-efficient models are your best bet. Hitachi's Deskstar 5K3000 and Western Digital's Caviar Green place at least as much weight on those two characteristics as they do on throughput. To achieve the best possible mix of performance and low power consumption, they employ slower spindle speeds. Thus, when it comes to performance, neither wins any awards.
The benchmarks show that, while the Western Digital Caviar Green WD30EZRS definitely doesn't break any records as a boot disk or a gaming drive, it performs well enough in the role of data storage. As a disk in a NAS device, for example, it'd excel.
The Hitachi Deskstar 5K3000 offers a slightly better mix of performance and power consumption, and thanks to a better performance per watt ratio, it's well-suited for large storage arrays.
You get significantly more performance with the Hitachi Deskstar 7K3000 and Seagate Barracuda XT ST33000651AS, if only for the simple reason that their 7200 RPM spindle speeds are significantly higher than the first group. Power savings aren't the primary consideration here, which is reflected in the less impressive power consumption results.
In larger storage environments, the Hitachi drive has an edge because it is more energy-efficient, while offering almost exactly the same performance as the Seagate device. However, don't expect extremely high speeds from any of these contenders; none of them should be used for server applications.
Understand The Terminology; Consider A New Platform Before You Buy
Aside from the test results, there are some points that should not be ignored when it comes to 3 TB hard drives. The venerable MBR is not suitable for hard drives larger than 2.2 TB. If you want to load Windows on a 2.5 or 3 TB drive, you have to format it as a GPT drive (GUID Partition Table) and boot with a UEFI-compliant motherboard. Because UEFI has not yet replaced the familiar BIOS in the mainstream space, and also because not every operating system supports UEFI, you should double-check hardware and software compatibility before taking the leap into a 3 TB disk. Even the simpler option of using the device as a non-bootable data drive won't work with every operating system, it'll certainly be problematic for certain NAS appliances.
Three terabyte hard drives remain premium products, not only because they're best handled by enthusiasts who know what they're doing, but also because they're the largest disks available and you always seem to pay more for the largest, fastest, coolest...well, you know the drill. If you really need ample space for your data, you have to lay a compatibility-oriented foundation first. Otherwise, it'd be better to stick with 2 TB drives. They facilitate similar performance, but they are clearly cheaper if you look at the cost per gigabyte.