I've been looking at others' cars and some use lowering springs others use coilovers. I recently bought a 2002 EM2 a couple Wednesdays ago and plan to lower my car soon so this will influence my decision of lowering springs or coilovers.
Lowering springs are exactly that, they just lower your ride height by a set amount, but give you a harder ride.
To do it the right way, you'll also replace your shocks.
Coilovers give you the ability to change dampening settings, adjustable ride height.
If you go with CHEAP EBAY coilovers, you're going to pay for it by a hard ride and shitty suspension. Go the right way, get Tein's or Form and Function's.
Coilovers are the way to go, no doubt about it. The extra cost is offset by the abilities to setup the car the way YOU drive.