Both give us power.
I don't think it is a case of either/or. Rather, it is inclusive. Both the ability to see black and white (meaning, Satan can't trick us into believing that good is evil and evil is good) and the ability to navigate ambiguities are blessings of discernment. When a person has to choose between ambiguous choices it is between several different good choices. Not a choice between something good and something bad. Eve didn't have a "bad" choice. She could choose to stay in the garden and be happy and innocent and in the presence of God. A very good choice. Or, she could transgress (move into a different state) and choose to move the plan forward. A better choice. Two good choices. Neither of those choices were evil but both would have certain consequences, so Eve had to use her judgment and personal revelation (she would have been baptized and blessed with the Holy Ghost I'm assuming, before she could have had a temple sealing) and gift of discernment to choose the best path.
Satan didn't trick her. He didn't convince her that staying in the garden was bad. She was far too spiritually prepared and in tune to be deceived by him. She saw the absolute of good and evil. She also, in her wisdom, saw the ambiguity of good and better and made the best choice.
Where the "absolute" part comes in is knowing the difference between good and evil. There is no absolute amongst the myriad goods.
PS--If there was no room to disobey Heavenly Father, then how do explain to childless couples that they have broken the commandment to multiply and replenish and as such are living in sin? Eve was warned what would happen should she make a certain choice. She chose to accept the consequences. That's different than willfully disobeying God.