A Link to the Past for me.
I couldn't help but feel that Twilight Princess was an attempt to re-capture Ocarina that almost, but not quite, worked.
Ocarina was amazing, but I can't help but feel that the game's a little threadbare. It was, in many ways, revolutionary. The problem being that I think that people were learning as they went, which resulted in an understandable lack of polish in places. Frankly, I feel the same about the first Zelda, by and large.
A Link to the Past was, for me anyway, the most polished. As with all Zeldas, the creators went for an epic and set themselves strong, solid goals. I think that this is the only Zelda where they hit every one of them dead-on, or without misstep or having to sacrifice something to hit it.