I haven't played every single LoZ game to date, but this is what I think for the ones I have played....based on reality.
Ocarina of Time: Malon
Majora's Mask: I forgot her name, but she lives at the ranch...about Link's age.
Twilight Princess: Ilia

Now if it was where anything was possible:
OoT: Zelda
MM: Though Zelda isn't really in the game, I'd choose her anyway
TP: Zelda, because I'd rather set myself on fire before I'd ever consider the LinkxMidna pairing.

Of course, my opinions are probably not as relevent as others I'm sure, but hey...anything's possible to an extent.

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/\ This is Link's job when he's not saving Hyrule/\
Expertly done by the wonderous ways of Necco