Zelda. She frequently surprises the player with how much of a badass she is.

In Wind waker she commands a gang of pirates many times her size. They respect and trust her and would follow her to the edge of the world. She also kills Gannon by bouncing an arrow off Link's shield. How badass is that? The hero doesn't even kill Ganon. Zelda does.

In Ocarina of Time, you spend all this time trying to save her after you saw her get kidnapped, only to find out she's the badass ninja who's helping YOU the whole time. She don't need no saving. She ain't no damsel in distress.

In BotW, you watch her struggle and struggle while she tries everything to unlock her power. Then in the face of certain death, she unlocks her power, and without hesitation, and without any training using her power, she fights Ganon for 100 years, holding him off to buy time while Link cooks food in his underwear.

In TotK, Zelda makes the ultimate sacrifice, trading her humanity to give Link back his trusty Master Sword so he can defeat Ganondorf. She also becomes immortal when doing this, so this is a massive sacrifice. She may never be reincarnated, as she's not dead. She has to live in that dragon body forever. It permanently altered her mind, too. She lost all her intelligence as part of the transformation. She's basically going to live in torture for eternity, but that was the sacrifice that she made without hesitation to give Link a chance to save Hyrule.

Link would rarely be able to save Hyrule without Zelda. They both have important roles to play each time.