What lift on an 08 Duramax?

So i've been going back and forth on what lift to put on my 08 lmm crew cab duramax. I want to be around 6". Right now i can get a killer deal on a full throttle style lift but my buddy swears they are "backyard engineered" and thus safety is a concern as well as ride quality. I've also looked into knuckle lifts from pro comp and fabtech Pro comp has the advantage because it pushes the front track out 1" vs 1.5" on the fab. Also looked into a pro comp 6" bracket drop but have heard bad things about the kit. I plan on runing 20x12 wheels and 33's, possibly 35's to help the ride quality. Right now the truck has a leveling kit and rides terrible so my main goal is to get the best ride possible without losing too much turning radius and blowing the bank.. Anyone have experience with these lifts on their trucks?