Those who know their stuff know that Ico is criminally underrated and didn't sell as well as it should've. It had some puzzles that would've made Link himself proud. The story was touching, with the bond between Ico and Yorda being as bittersweet as that between Link and Zelda. But it just didn't sell as much as Ocarina of Time, nor did it have quite the same culture impact. And that's exactly why I'm voting for Ocarina.
OoT does everything Ico does, the captivating story, the mind-bending puzzles and the genius design. They're almost completely even, but OoT has had the bigger impact and sold better. And that's the only thing I have to decide my vote. But I'm hoping that everyone gets the Ico re-release. It'll be worth every penny and it'll be jaw-dropping in HD.