The main choices people have here are likely Navi, Tingle, and Kaepora Gaebora. I'm going to go with Kaepora Gaebora.
Navi does get annoying if you're replaying the game, but if you haven't, she can help you a lot.
Tingle, while being extremely creepy, at least helps you out in all the games he appears in.
Kaepora, on the other hand, has absolutely NO PURPOSE IN THE GAMES HE APPEARS IN!! In nearly every instance you find him in OoT, you can figure out what to do on your own.
Hyrule Field: I'm sure everyone has taken a look at the pause menu at this point.
Hyrule Castle: You have to get caught by the guards anyway, so why warn us?
Death Mountain: One of the few instances where Kaepora helps by bringing you down the mountain, but not before he tells you about the Great Fairy who EVERYONE has told you about before.
Lost Woods: We already figured out that we need to listen to the music. If he's going to tell us, tell us at the beginning of the woods.
Zora's River: Playing Zelda's Lullaby might not have been the first thing to come to mind when reaching the waterfall, but I'm sure people can figure it out when the inscription says something about "slumber".
Lake Hylia: Tells us about the Water Temple at the bottom of the lake. Navi's going to hint us to use the boots to sink into Lake Hylia anyway, so this serves no purpose.
Desert Colossus: Tells us how to beat Twinrova. Isn't that Navi's job?
I'm not going to say anything about MM, because I haven't played the entire game yet, but I think I proved my point.