My pick...the CHI Pro Low EMF hair dryer (pictured below with concentrator nozzle attachment).
This is their basic, no-frills model, and for the money, their best. Two speeds, cold shot button ... couldn't be easier to operate. It comes standard with a diffuser attachment and concentrator nozzle. But the best features of the dryer, personally, are its light weight and negative ionic charge.
What is negative ionic charge, you may ask?
Simply put, it helps to break the water molecules in your hair down into smaller particles, thus dispersing moisture more efficiently, requiring less heat to dry the hair (and thus the cuticle does not open as much and consequently compromise hair integrity) and ensuring a quicker drying time. If you are diffusing your hair and wish your curls to stay beautifully formed and shiny, negative ionic charge is a must.
The CHI Pro Low EMF is available at many online retailers, as well as ULTA stores. Expect to pay about $110 for the dryer. An investment, but entirely worth it.