I love ALTTP. Overall, it is still my favorite Zelda title. For me, the leap to the SNES was an important one, and to see a Zelda installment on that console was invigorating. I had wanted AoL to be like LoZ; and while I still enjoyed AoL, I was very happy to see the top-down style of gameplay return. The upgrade to 16 bit was more than I had expected in terms of graphics, sound effects, and music, but you've got to hand it to ALTTP's incorporation of gathering the 3 medallions before the Triforce hunt. Nintendo found a way to extend the game in a rewarding way, and I enjoyed that immensely.
Honorable Mentions: (in no particular order)
Light and Dark World (with the funny bunny transformation)
That trippy witch in the woods (can't remember her name right now, but she stirs that cauldron like crazy)
The big map (nice to know where you are)
The ability to dash at enemies (and across the screen to speed things up)
A story that's deeper and keeps the player involved
The flippers (which are just plain awesome)
The return of Moldorm (but as a boss that is by far the biggest pain of the game; rock on)
The Master Sword is GOLD (what?)
Super bomb (when a regular bomb won't do, use the big pink one)
I'm not listing all of it. Someone else go; there's a lot left to mention.