What Justin fails to mention is that if you have a 5spd truck or even an early 6spd truck you will need a larger input shaft to use a Dual Disk with your truck.
Justin and myself are very happy with our South Bend Dual Disks. I know of several people who drive on Haisley DD's everyday and pull sleds, but I've heard that Enterprise's clutch isn't the best "street friendly" clutch. However, EEP's clutch ranked very high on the pulling track for the past few years.
If your gonna drive it everyday I would go with SBC or Haisley. I was torn between the two myself, but came across a sream'n deal on a SBC which made my mind up for me.
Call all three vendors and discuss what you need your truck to be able to do (haul, etc. ) and what you would like to do it, and I think that will help you determine which would be best for you.