What kind of performance do you need?
Flex for rocks?
Stiff for mud?
Something in between for trails?
Pirate4x4 dot com would probably be your best resource for tech info.

If you are looking for a stiff "Mud" suspension, then leaf spring will do just fine. The amount of lift will be determined by your budget, desired tire size, and type of truck. If you are wanting to crawl up rocks, then almost nothing beats a 4 link with coil over shocks. If you are wanting more of an all around rig, then soft leafs, coil springs or a combination will do just fine. For more of a custom setup, you can use Peterbuilt or Kenworth Air Bags with limiting straps. This gives you complete control and adjustment of ride height, Flex and articulation, and most of all it is a very soft and comfortable ride. I would not recomend this for a rig to be driven on the road since it is very unpredictable at high speed unless you have a lot of weight on it. I will never go back to springs after doing this. I use a double bag progressive setup with and engine driven compressor and 2 other dedicated 12 volt compressors with a 10 gallon tank.