I have run both separately and I'm not sure that I have a strong opinion on one being better than the other.
Although thinking about my run this past summer, when I stacked both with Phosphatidic Acid XT, I actually hit new PR's on my deads and bench. They are an interesting product in that you don't feel some sort of weird stim or anything but your gym sessions get like this extra oomph. more energy and focus, and I think added endurance allowing longer and more effective sessions was my experience.
now I feel silly cause I'm running only one of them but should probably be stacking them! might be time to order a bottle.