What do you want to do with it?
There is not much point in buying a fast HDD for "home use". These buggers are rather noisy, use a lot of electricity and convert most of it into heat like lightman said.
What kind of motherboard or sata host adapter do you have? Does it support drives larger than 2 TiB?
For optimum performance it would probably be better to install the operating system and your favourite programs and files on a (small) SSD. Then you could use any "slow" drive for your large files collections like the Caviar Green series.
The Caviar "Red" drives have a higher data density and therefore are a little bit faster and use even less power than the "Green" drives, but unfortunately they are optimized for RAID.