Id go with coilovers, plain and simple.
Springs will give you your drop, but if used in conjuction with older shock absorbers, the car will bounce all over the road, and because the shocks are now working at a different height the seals soon give in and they burst.
Springs and shocks kit, more expensive, doesnt bounce all over the road, but dependant on what kit you either get a bone shaking ride, or a sloppy one, and a lot of the time with spring/shock kits as with just springs, you end up with the front lower than the back, and vice versa.
I spent £200 on my last car, on springs, then i bought gas shocks, before fitting coilovers and wondered why i didnt go coilovers first.
The leon i bought is lowered and i only realised last week the reason for the perfect even drop and comfortable ride is because its on adjustable coilovers, you can set the height perfect, and the damping to how you want it, best of both worlds.
