Lots of options for doing either or both but....I am curious what are you trying to achieve. How do you use your car? What about the stock brake performance do you want to improve?
My opinion...for a street car, even one that you drive in a really spirited way, totally rebuilt stock brakes with Porterfield or Hawk pads (and probably other brands too) work really well.
And, along with pads, another way to improve stock brakes would be tires.
I do track days with my MX-5 and braking is amazing. If I were to do track days with one of my zcars, I would probably start with stock brakes, track pads, and Castrol SPF brake fluid....and track appropriate tires. I bet I would need to improve my driving before I found myself needing better calipers, converting rear drums to disk, etc.
Anyway...I don't mean to sound like I am discouraging upgrading. I have thought of doing it too....but usually remind myself how well the stock brakes work and then find something else to focus on. Just curious about your goals and thought process.