Just know that the HD204UI/VP4 inside the Samsung Story HX-DU020EB/A62 is a specially customized version of the HD204UI, quite different from the bare drive OEM version.
The HD204UI/VP4 (Story version) is configured to spin down crazy often. This is done on the drive itself, not on the USB...
Whichever one you choose, pick one with the ASMedia ASM1051 USB 3.0 chipset. The JMicron USB 3.0 chipsets aren't there yet.
I like the Vantec NST-330SU3-BK (39.99 from newegg). It has a switchable fan and easy drive installation. Plus, an eSATA port in addition to USB 3.0.