I would say start with a link to the past, a link between worlds, then start the 3D ones. In that order. Then, if they still have the itch to play more zelda, go for the Ds ones, and lastly, play the original zelda, and zelda 2, the adventure of link, I say that one last, just because it's completely different from the others.

A Link to the Past is probably the best to start. However, if you find a map and use restore points on WiiU or 3DS, I think the original Zelda would be a great option too. I just played it for the first time last year and thought it was amazing without all the frustration.

Any of the 3d ones or link to the past, the DS games are hit or miss for a lot of people.
But I started with Phantom Hourglass

The first Zelda on NES. If people want to experience any franchise, they should start where IT started and work their up forward through all the advancements until they're caught up.

I agree about Ocarina of Time, good intro. Twilight Princess could work too. 

I'd say to stay away from Wind Waker, the story didn't do a very good job of explaining the world of Hyrule, and the whole "Hyrule is underwater" thing is more of a throwback to those who already have traveled in it from other games. 

Of course, I'm jaded on WW, I call it "Nintendo's Philips CD-i Zelda", or the "Phanton Menace of the Zelda series"

You're not refering SS as a 2D game, right? Because that would be incorrect.

Play Ocarina of Time or Majora's Mask. This is the height of the series.

Then play Hyrule Warriors and if you still yet like that, you'll like the rest of the series.

ALTTP is definitely great game, but not everyone can play top down 2D game from 4. generation of consoles, and definitely ALTTP can be little complex and hard for todays gamers, so I relly dont think its best choice for first Zelda game even it offers maybe best Zelda core experience.

Majora's Mask is actually probably worst choice for first Zelda game, its very different from other Zelda games and its most complex.

I always say Ocarina of Time or Link to the Past are the best to start with. I don't say that because they're my two favourites (they're not), but they're what I consider the most "pure" Zelda games that aren't too hard to get into like the original NES one is.