Another ALTTP fan here.
My justification:
- Was the most serious-toned (and possibly darkest) Zelda game IMO. A lot of fans will say MM or TP were darker, but both those games also had a lot of silly, childish elements that broke their seriousness.
- One of the best in terms of that open-world, exploration feel (though WW may have a slight edge here.)
- Was groundbreaking in so many ways and pretty much set the formula for all future Zelda titles. Just about every "Zelda-ism" you know, things like "every dungeon has a map, compass, and big key" originated in this game. Sure, people are getting sick of the standard Zelda formula now, but in ALTTP it was original.
- Wasn't nearly as linear as the 3D Zelda games; you could do the dark world dungeons in a lot of different orders, and there were quite a few optional, but valuable items, such as the cape.
- Just the right difficulty, you'll die a few times, but it's not frustratingly difficult like the first two Zelda games.
- No gimmicks, just pure Zelda.