being lowered on springs gives it a nice look, but if you plan on carrying passengers and other equipment, i wouldn't recommend it. i used to be on lowering springs and though the spring rate was a bit stiffer, it would still create a long spring travel. if you go fast over a small bump or a pothole on the freeway, you would bounce for a few seconds (really depends on what it is though). i remember carrying 2 passengers in the rear and going over a water gutter, and it made a horrible scraping noise.
after upgrading to coils, i noticed a huge different when driving and going through similar situations. i would recommend getting coils only because it gives you more adjustable options. you don't have to slammed it to the ground, but you could also give it the same look as lowering springs (about inch and a half drop). plus you don't have to worry about bouncing so much because of the stiffer spring rate and shorter spring travel