Best answer - stuff is situational.

Extended Balance will give you more overall output than Enhanced Balance but if you need more output faster, Enhanced will give you that. If a mechanic is going to occur within 45s that causes a boss to go invulnerable for a decent portion of time (Oppressor jumping), then a decent part of Extended will be lost and Enhanced will be better.

It's up to the AST to determine what is "best" at the given situation. It's one of the unconscious rewards for playing the class well.