Short List
Springs:
Pro - Cheap, Affordable, Comfortable, Straight-forward, Improved Handling, Better stance, Preset height adjustment.
Cons- No adjustability IE Preset Height Adjustment, Not able to adjust dampening, some stock struts are not made to handle your car being lowered on springs so your struts will wear quicker,
Coilovers
Pros- Come with new springs and struts paired together, Adjustable height and dampening(in most cases, some do not offer dampening but height only IE Bilstein for the Mz2), Improved Handling, Improved Stance, set to your likings
Cons- Expensive, Also expensive in order to be comfortable(IE Expect to spend 1.5-2x more money than the cheapest coilovers on the market to be "comfortable"), Harsher ride in most cases, must have basic suspension knowledge to make your car ride correctly and handle correctly.