I would have to say Alttp for me as well, at least for right now. Although it can be said that this is the first "modern" Zelda, This was really still a transition period between the days when Zelda resembled a jRPG and the days of Ocarina of Time. If I was to ask you to think of a Zelda game when I said something like "GET THE MAGIC FAIRY CRYSTAL FROM THE MAN ON MEDICINE MOUNTAIN" the first two games would probably come to mind. The thing is though, Alttp really still has some more primitive elements that make it beautiful.
For example, while some dungeons (keyword: some) had items that played an important part to the dungeons themselves, others were not afraid to give you something totally optional, like the Blue clothes. Then other times, they were literally like "lol idunno" and just tossed the very magical ice rod in a cave next to the lake. Both of these elements were *awesome*. It made the game feel a little less formulaic when you didn't know what to expect. Also however, I would like to give mad props to the overworld design in some places, especially near bodies of water.
If you don't know what I mean, go stand out on the peninsula east of Lake Hylia (you can see it on the map), or go stand on a ledge at the waterfall of wishing. It's a powerful, beautiful feeling in regards to nature.