My money's on EcuTek
It's pretty new so there's limited results information available and minimal dyno charts, if that's what you need. I'm currently in the drive cycle of my EcuTek tune on mostly stock Z and still data logging the car for fine tuning. I will post dyno sheets once we get the tune finished and find the time to dyno, but that probably won't be until the end of the summer. There is also a slow adoption with the forced induction crowd - people are understandably hesitant to test out new software on their TT or SC setup.
UpRev is probably the most popular tune for the 370Z. It has been around for a number of years, but it can't do quite everything that EcuTek can (like VVEL adjustments). FWIW, my tuner uses both and claims that EcuTek > UpRev.