I'm not sure there would ever be any definitive answer to a comparison, as personal preference would likely come into play. That and perhaps the FIRST product learned would possibly be that person's preference. I talked to two guys who are pretty much highly regarded in the tuning circles and one preferred HPTuners, and the other EFILive. The one who like HPTuners said it was easier to work with, and the guy who liked EFIlive said that one was just better (without explanation - which at the time I likely wouldn't have understood anyway).
I played with HPTuners at first, just using the scanning function when I first got my C5Z, and then switched over to EFIlive rather recently when I started doing actual tuning tweaks. But honestly I don't feel I have enough experience under my belt with both of them to form an opinion as to which one I felt was better.
__________________
|