I want to buy a 3TB hard drive to store my media files, but I wonder if I should buy a NAS hard drive versus a USB 3.0 version. Which one is faster? Which one is easier to set up? Also I'd like recommendations where to buy NAS or a USB 3.0. Thank you.
A NAS with gigabit ethernet will get a max about 100mb/s transfer rates and a minimum of about 80 depending on the drive and network traffic.
A USB3 drive will be limited by the max speed of the drive inside. Typically the 3TB drives are 5400rpm and avg about 125mb/s and a minimum around 80mb/s.
Where to buy depends on where you live. Check you local sales ads. Read reviews of ones your interested in. Compare pricing with Microcenter, Frye's, Amazon, and Newegg if you're in the US.
I'm curious as to where you store your current backups for when your pc's harddrive dies? It doesn't sound like you already have an external drive for backups and you should never trust your important files to be stored in only 1 location.