The #1 question you need to ask yourself is:
What am I going to use the truck for?
If you are just going to use it for a truck, and leave it mostly stock, and just want a little power up, most of the tuners will get it done.
There are 4 basic kinds of tuners:
Harness Boxes: Like Edge or Banks, these plug into your bale connector and intercept the engine electrical signals and increase power that way. They cannot remove the 96mph speed limiter, nor truly correct for tire size changes. They are very convenient, and often come with gauge options built in. Good choice for those who are going to use their truck like a truck only. You will not get competitive racing power out of one though.
Handheld ECM tuners: These "re-flash" your engine computer through your data port. They can correct your speedometer and some can display engine data on the handheld unit. PPE makes the widest range of these, and the most powerful. They are very convenient, and are also good for "truck" usage at the lower power levels. At the high power settings, they are full race capable.
EFILive: This is a custom tuning and programming system. It is the most flexible system, but like all professional tools, is a bit more complicated. You should have a good understanding of how to use a Windows computer, and should have a notebook computer available for use. Soon the need for a notebook will be removed. It can build tow tunes through world record competition engine tunes, and everything in between. It also records and displays engine operation data.
Locked/Preflashed ECM's: You buy these mail order, and they are pre-programmed for your application.