Which scanner is the best?

[bcredliner]

I need a scan tool that will monitor all cylinders while I am driving and show any variances in performance by cylinder such as a miss, air/fuel, spark etc. I don't want to have to watch it. Could be as simple green when OK and red it not. If there is nothing like that a graph by cylinder that I could look at later would be better than nothing.

I would mount it and have it there all the time. I would like it to work on an iPad but I would buy what is needed for another operating system.

Any suggestions?