Question: what is the fastest way to transfer files between hard drives?
Answer: USB2 (500 Mbps), always choose USB3. If you need 2 such ports, use a hub. The maximum transfer rate of a USB2 HDD is around 30 MBps, and on USB3 still x10. 3- if you use Windows explorer this can be very, very slow, mainly if the number of files to copy is a couple of 10.000s.