Eibach Drag-Launch Springs....

You're comparing apples and oranges. The drag launch kit is not a lowering kit. The prolines and sportlines are. The drag kit will ride nicely, the lowering kits will ride much harder in comparison. Do you want to drag race or corner?

Most people cut a coil out of the drag launch kit. If you've lightened the front end at all (fiberglass hood, aluminum heads, battery relocate) the drag launch kit will usually raise it up from stock, not lower it.
 
I have the drag launch kit and it rides fine on the street. Not much different than stock really. The rear is lower than stock by just a tad, but the front is WAY higher than stock. I can only fit one finger in the rear gap (between tire and fender) but four fingers in the front. I have a few weight-saving mods up front... fiberglass hood, no A/C, no P/S, no smog, no sway bar, battery in trunk, etc, but no aluminum heads or anything major like that.
I know that this ride height is best for weight transfer and traction, but I still may eventually cut a coil or two off the front springs to get a more even front/rear height.
As mentioned already, it depends what you want to do with the car. If you're going totally for the drag thing, the drag launch is best... but if you ever do any spirited corner carving, forget it. Up front I have the Eibach's, 3.5" welds, and no sway bar and I have to be careful how fast I turn. It's more of a "straight line" setup. If you're simply going for an appearance mod, like a nice low even height, some lowering springs would probably be best. The drag launch kit isn't for appearance at all, it's purely for function.
Hope this helps!

imag0001.jpg