Lowering springs and coilover sleeves can have a great ride and handling if you use quality products and good struts.
Lowering springs are shorter/stiffer springs
Sleeves are shorter/stiffer springs with an adjustable collar that fits between the spring & spring perch on the strut.
It all depends what your going to use the car for. Any type of adjustable height is a pain for street use if you plan on actually using the adjustments. After each change in ride height you have to get an alignment and corner weighting is rec. Do you really need that for the street? No.