Desktop spinning hard drives for the most part are no longer the primary storage device in most computer systems, that is of course if you have a computer that is 4 years or old. Traditional spinning drives have been replaced by the SSD as the primary storage drive of choice,they're faster,boot times is speedy and since they're not mechanical,they don't consume a great deal of energy.
With that said,spinning drives for most part still serve a purpose today,they can be used as internal backup drives. I for one when building a new system, included with my SSD is a spinning drive which is a added source of data backup.
If you're in the hunt for a spinning hard drive and plan on using it for internal backup or upgrading to a much larger storage capacity,point yourself right over to Micro Center. They have a 3.5-inch 2TB Seagate Barracuda SATA III hard drive with 6Gb/s of data transfer speed for just $69.99.