It was between JB3/4 and ESS for me. I went with ESS because of the DirectFlash unit which allowed me to do it from home. It is such a simple process if you follow the directions but the results are so amazing. With the ESS Stage 2, it is like a whole new car. The engine runs so differently and even sounds different (more muscle).
It takes about 15 minutes to write the new maps and you're good to go. When I need to take it into the dealer, I just plug in the DF and I'm back to stock when need be.
I couldn't recommend it more.