It all depends on what you can spend on each. IMO - the longest stroke will always get the nod from me. The two engines are very close. The 383 will add more value to an E body and most people like looking at one more than a small block. The 5.9L will get better milage and is easier to work on because it's smaller. It will also IMO be more responsive in a street driving arena due to the 3.58 stroke. So if the money's there for the transmission, driveshaft, and mounts/kickdown then the 383 might be a better payback. The 5.9L will drop where a similar small block was and feel quicker - all other things being equal.
And yes - either engine can be built for better performance...lol