In my opinion, it is best to do a bit of everything, because you would be getting the best of each training approach. Each approach will have its own advantages and disadvantages. I like those unstable, as you call them, exercises, because them employ lots of small muscle groups that are meant for stabilization, so they will condition you much more in a functional way. But the usual approach to training has the benefit of better and safer muscle growth. So in the end of the day it will mostly depend on what you want to achieve.