Never used the dropped LCA's. When I was a newbie to this lowering stuff on GMT400's, I was told to avoid them.
Apparently, and this is just from word-of-mouth, second-hand info, they can cause alignment, premature ball-joint wear & ground clearance issues.
Dropped spindles & springs are the most common, proven method.
2/4 drop? A lowered spindle will retain the stock ride characteristics, IF that's what you want!
A lowered spring will LOOK like it's made outa thicker steel, (it is) but it retains the same spring rate as a stocker spring. It's just shorter.
Cutting your stock springs will increase the spring rate, making the vehicle ride a bit more harsh than stock, but it will make it handle like it's on rails,(!!!) if THAT's what you're looking for.
DJM & McGaughy's spindles don't push the wheels out like the Belltech's do, which can be remedied with wheel offset, but you can find more wheel designs off the shelf with standard issue offsets. Stock 15" wheels will work with all of them. Just gotta trim those LCA's.
Belltech spindles were designed back when a 17" or 18" wheels were considered huge & they push the wheels out to clear the LCA's.
Shackles are pretty well the same manufacturer to manufacturer. A simple design that's pretty hard to screw up.
Just make sure that the upper part of the shackles, near the box floor, are rounded off, not square cut. Without being rounded off, they MAY contact the box floor & wear some nice little holes in the floor. (How do I know this...? Hmmm...!)
Hope this helps in your decision!