I would always suggest to
Get an internal 2TB harddisk and an external casing from Transcend / Sunbeam
This way, your data is saved from interface failures
If there is any failure with the interface, the external drive would be replaced, but whole 2TB of data is gone
I had this bad experience where a Seagate Freeagent drive failed in just 2 weeks. The drive was replaced with a new one, but the entire 1TB of data was gone
These days, I use internal drives with the built-in HDD dock from CM 690 II Adv
Its a brilliant option, HDD gets detected as internal drives (not esata or usb) once connected and the transfer speeds are as good as internal drives
Its not plug and play, but damn worth it, I can copy 400GB of data to it in an hours time
