Power.
With power, you can essentially do anything you want. With the snap of a finger. You can fly, you can teleport, you can shoot lightning out of your fingers (lol), you can read & control minds, etc etc.... Need I go on?
Wisdom and Courage are both easily gained attributes. I already have those both anyways.
Besides, The Triforce of Wisdom seems useless in my opinion... Because if it truly made you KNOW everything, then why didn't Zelda in OoT see her imprisonment coming and have Link or herself counter-act it? (Or is POWER just too much for Wisdom to handle? heh)
Sure, the Triforce of Courage may have a point made in the example of Link's bravery, but I think his courage just comes naturally.
Remember, the Triforce is a balance that weighs the 3 forces, only the force that one most believes in is the obtained. So Link and Zelda already had a huge amount of Wisdom and Courage before they even got the Triforce. I'm sure Zelda, in her training as a Sheikah (obvious in OoT), has gained quite a sum of Wisdom from it, and with her knowing the future events in the form of Precognition... Well, I guess that results up to her having Wisdom?
But anyways, again, my choice is Power.