I have been driving a '19 M3P with H&R springs and stock shocks. Depending on your use of the car, I may or may not recommend it.
- H&R springs are GREAT for looks when combined with spacers.
- H&R springs are stiffer than stock springs with less vertical compression and extension so the H&R springs have a harder time damping movement if you keep the stock shocks. If you drive spiritedly, especially noticeable on hard corners where the pavement has bumps, the stock shocks cannot sufficiently damp the movement and the car tends to bounce around and twist as a result. Very scary when at the limit.
So, my entirely un-professional internet opinion is if you just want the looks, get springs and know that in some situations, you will not be in a good situation. If you want good handling, you could get upgraded shocks as well...but then you need to be a suspension engineer to pair the spring rate to the new shocks (or get adjustable ones and try out several settings). At that point, the additional cost and effort warrants just getting coilovers. They already have had the engineering and testing done (if from a reputable brand).