Food for thought, I did my '05 axle swap and 6" fabtech lift for well under $2000 by hunting for deals on used stuff. I still have to buy and install the PMF 3.5" shackle flip in the rear and add the higher capacity '05 rear leafs, get a new driveshaft made, and rebuild the brakes on the '05 rear axle, and even with all of that I'll still be under $2500.
If you're staying leaf, BDS is pretty hard to beat for quality and their warranty is stellar. A lot of people don't know that Zone Off-road is a BDS offshoot and it's basically the same quality components without the fancy shocks and the warranty to keep the prices down. And I wouldn't overlook Fabtech. We had a 4" kit on my buddy's '03 V10 CCSB and it rode great, even towed great because it kept the stock rear leafs.
Most of the complaints about ride quality on lift kits comes from torquing things like the spring eye and shackle bolts and the track bar with the weight off the tires. It binds all the bushings up and won't let things move the way they are supposed to. Same thing happens with lowered cars. To that end, get the most quality your budget allows, then take the extra steps to make sure it's installed right. That's the difference between some guys complaining about their lift and others with the same lift being really happy with it.
