I had a tough decision between the 4 races that are in Ocarina of Time excluding the Hylians...seriously, Hylians are basically humans, so why would you want to be one if you had a chance to change?
Sheikah - It would be awesome to have the martial art and acrobatic skills that the Sheikah show, but I'm not sure if that's just Sheik or not. It would be awesome to be able to use those abilities in a fight though, or in an invasion of enemy territory, but I can imagine that they'd live a fairly strict life outside of that, which would be quite annoying to put up with.
Kokiri - I think it would be great to be a real life Kokiri, because you wouldn't have to grow up, and that means you don't have to worry about anything like Education, Work or any other stressful time taking things that life throws at you. You'd be able to do what you wanted all day and night, the only weird thing being that your parents would be the same age as you, along with their parents...etc. The only downside to all of this is that the Kokiri aren't meant to be able to leave Kokiri Forest (although the ending of Ocarina of Time says otherwise)...
Zora - The Zora has the awesome ability to move around on land like a Human, but also the ability to live under water for extremely long periods of time, and are excellent swimmers. It would be a great advantage to have over other races, especially if a natural disaster was occuring, or a shortage of food, because you'd easily be able to hunt on either land or in water. I'd like to be able to swim like like the Zoras can (especially with the Zora Mask in Majora's Mask), it'd be awesome to do and it would allow you to do a far amount of travelling around the world too.
Goron - However, the Race I choose to be were the Gorons. It'd be awesome to use your huge amount of strength for different things such as sports (like Sumo Wrestling) or rolling for both fighting and sports (like the minigame in Majora's Mask). It would definately be cool if you were able to roll like Link can with the Goron Mask in Majora's Mask, because you'd be able to roll both up and down hill, or possibly upside down along something if you could build up enough speed. I'm not sure about the rocky diet though, because I'm not really sure how it would be enjoyable, but then again, you'd have a Goron's sense of taste. You'd also be able to withstand intense heat too, which is just pure awesome. I guess the inability to live under water would suck, although that's up to debate thanks to the Goron in Twilight Princess.
So yeah, ultimately, I'd like to be the Goron.