Ocarina of Time, no contest.

If play with 3DS is ok, play OoT. If want to play first zelda with big screen, WWHD is the best.

Pretty much this, and then /thread.

After playing ALTTP, I would reccommed going straight to Ocarina.  The original NES games haven't aged all that well (plus they are HARD compared to modern games, especially Zelda II) and the newer 3D games in the series like Twilight Princess and Skyward Sword might be a turnoff to newcomers.

A Link Between Worlds is very accesible and very addictive, and is also heavily inspired in the best Zelda ever, A Link To The Past, but it feels way more modern for obvious reasons.

wut? skyward sword 2d? ok then. but yeah im waiting for a SS remake-remaster too cos dont like old SD graphics or motion control

Skyward Sword easily. The game is accessible and its handholding it's like a tutorial for the next games. In fact, playing accordingly to the timeline is good.

I think the nature of Zelda makes every single game accessible to newcomers. Only exception is Majora's Mask, which had some elaborate mechanics that are easier to understand if you play a more normal Zelda game (... like Ocarina).

Throwing someone to a 3D Zelda for the first time might be too much for him/her, I know that just too well. Is too complex for some people. I would start with a 2D game, but not something hard like the first Zelda or ALttP. It shouldn't be too outdated visually speaking, some people don't like that unless they already love a series. Also, it shouldn't be too long to beat. You have to think about this first contact as a "demo", he has to realize if he likes it or not, so you can't give that person a 25-30 hour game to the face.

I think the best ones to start are A Link Between Worlds and Minish Cap. I started with Minish Cap and now I'm a great Zelda fan.

I would say The Wind Waker or HD

I agree. The original zelda just doesn't hold up well today. A link to the past is still an amazing game.