personaly i'd get the SCT Xcal 2 over the preditor and superchips. just my bias as it has everything i want, and the guys at SCT are VERY helpful. plus it helps that a lot of tuners use SCT tunes for their customers, so it makes it easy to change things after you get a custom tune.
diablo from what i have heard has the best out of the box tune from diablo, especially for cobras. it works welll, and has a nice display. it does not have everything worded well so some things CAN be misleading. and i have no knowledge of superchips, so i cant comment there.
Torinalth