You want one that will do true usb3 speed and not one that is really only capable of usb2.
I've used a few of these
nextstars and they are capable of 400MB/s sequential read and write. Not that your HDD can hit those speeds, its just that you do not want one that can only do 40mb/s.
You also want to avoid ones with an auto-sleep function. Rosewill Rx307 for example...
{ The Nexstar does not have autosleep }
Happy shopping.
