Anything that can connect to your phone is great honestly. Bluedriver, Veepeak, OBDLink are all great OBDII readers that use apps on your phone as a scan tool. I would do research on which app gives you dealer-level diagnostics, and then buy whatever OBDII reader that app supports. I personally like these app-based readers because I can data-log very easily while I drive and save those logs on my phone to view later. But of course, you can buy a physical hand held OBDII reader as well...Autel is a good one (Scotty uses them in his videos too). 

For example, I bought the Veepeak Bluetooth reader to access dealer-level diagnostics for my BMW using the BimmerLink app as well as code my car using BimmerCode. 

You just have to do some research. Good luck.