Well, my mechanic suggested the following- the swepco is the best, especially for hard use. Its thick. But, he told me that driving around town, and when its cold out, that perhaps Mobil1 Tranny fluid is best. So at the moment, I am using the Mobile1. But the Swepco is a pretty cool blue color
Seriously though, when I put in the Mobil I could feel the shifts get smooth much sooner after startup, meaning the fluid was ready to go at a lower temp.
No matter what, changing it regularly is probably far more important that what you use anyhow.