From what I have heard, if all you want is ODB-II information, folks have said the ScanGuage is pretty good. It doesn't get hybrid specific info though, such as MG RPM/current, or battery voltage/current/soc.
There are dozens of options out there and they vary by your needs. With Prius you'd also want CAN data. AFAIK there are no current commercially available aftermarket options that include the hybrid specific data, however.
Someone posted a link the other day for a very slick looking Bluetooth scan tool, but it was pricy and OBD II only (no CAN). You can look at PriusChat or do a search online for that.
If you've got money falling out of your pockets and want the best of the best it's possible to buy a genuine THHT scan tool that would allow you to do everything your dealer's tech can do plus get full access to all hybrid information. Definately the best option for a true techno nerd. You're going to be well over a grand for this tool.