"Best" and "economical" are going to be polar opposites when it comes to picking out a lift kit. Best, in terms of quality won't be cheap. Economical will mean low quality parts that you'll be replacing all the time or bad ride quality or both.
There are certain mods that you don't want to cheap out on. Spend good money on a quality kit and your rig will thank you. Suspension is everything, especially on our vehicles and what we do with them. You want quality parts under it, and that means your going to pay a decent amount.
I've got a Rock Krawler 3.5" lift kit, all inclusive kit (meaning all the extras besides the usual shocks\springs) and I couldn't be happier. Took me a while to save up for it, but I'm very happy I waited and bought a good quality kit that's going to hold up to abuse and give a great ride quality.
Buy once, cry once.