Who do you think is more annoying? I have to say Navi since she states stuff that's way to obvious. Also: The least annoying character will get a celebration.
Without Navi Ocarina of Time wouldn't be the same. She annoys me mildly, but I like her. I actually think Midna is really cool, she's not as annoying as the other two, plus it's funny how she's condescending all the time. Fi is by far the worst, not only does it piss me off beyond anything that she's autotuned and a really boring character, but her information is 90% of the time downright useless and annoying. Like how she informs you that you're running low on hearts, it's like "oh really? the super annoying beeping sound didn't make it obvious enough", plus how she tells you that "your batteries are nearly depleted" when you can still play with them for HOURS.
I haven't played Skyward Sword./disappoint But I really like Fi's design, even if it is based upon the Master Sword. Out of all three though, Midna is my favorite sidekick, if not for being a total tsundere, then for being super smexy in her humanoid form. Navi is annoying, I'll give you guys that, but she had Link's best interests at heart, and who could ask for a more caring sidekick?