For a shackle lift, anything over 1" lift is getting to be too much because for 1" of lift the shackle needs to be 2" longer. Also they can cause problems with driveline angles in the front. Plus if you plan to offroad much they reduce your approach angle.
Body lifts are cheap and for larger lifts they look ugly.
Depending on why the reason for the lift, I probably would be more inclined to go with a 1" or 2" body lift. I have a 1" BL on my Jeep and 5/8" shackle lift