Hello, new here

I am shopping for an OBD to USB adapter to do data logging of my 2009 Prius. I would like to log data from various ECUs in the car so I may end up writing the software myself, unless there is existing software that is capable of reading and recording customized combination of various generic and Toyota hybrid specific parameters. Please advise if such software exist. Thanks!

Also the question on which one to buy:

What is the difference between
ElmScan Compact 5 USB
http://store.mp3car.com/ElmScan_Comp..._p/com-101.htm
and
OBDLink Multiprotocol
http://store.mp3car.com/OBDLink_Mult..._p/com-100.htm
?

They seem to support the same set of protocols:
ISO15765-4 (CAN)
ISO14230-4 (KWP2000)
ISO9141-2
J1850 VPW
J1850 PWM

Thanks!