I don't know about consensus because I have only used one . it is an elm327 , they are small and don't stick out far from your obdii , on ebay about $6.

it well show you iat's , rpm , throttle position , short and long term fuel injection correction , boost and a bunch more . I use it with torque pro from the app store ($5)

I thought was I could start with that then buy something else if needed , haven't found a reason to buy anything else to this point .

I do want to buy an afr gauge to add to it .