I, as well as many others on this site, will strongly recommend the DiabloSport Predator. I have a Predator in my truck, and I couldn't be happier with it. I has proven to have great results, especially with the 'Diablo Tune' (It has an 87 Octane tune that I use most of the time, and a 93 Octane 'Diablo Tune' that gives you even better performance for premium fuel). The Predator also allows for many, many fields to be adjusted so that once you learn what each is and how to adjust them, you can make it match the exact way your truck runs. It can also log data download tunes so that if you want to, you can have a DiabloSport tuner take the data you log and write a professional tune to match your truck. We have a user on this site, 06monteSS, who is one of the tuners for Diablosport, and I have heard nothing but good reviews about his work.
This information is based on my personal experience with my Predator, so I hope it helps you.
Be sure to let us know what you choose in the end.