Yates, Gentle Typhoons are popular, but you can fill a rad with Yates for the price of one GT practically and the performance difference isn't that extreme, same story with the Triebwerk fans which are supposed to be designed for pull situations, but they're nothing special, they're just thicker, performance is average at best, definitely not the world-changing performance they advertise.
Edit: I'd go with the highspeed and get a fan controller. They're loud on high, but turned down you won't notice them. I try to run my rig silently so I've got everything turned down, but I like being in the low end of the power curve and being able to turn them up if need be, instead of constantly running them on high. I believe the model is something like YL120HS or something to that effect.
Edited by SaltwaterCooled - 1/9/11 at 10:46am