I've played many games in the Legend of Zelda series, but I've never really played the first one until I got the NES Classic (my first experience with the series was Zelda II followed by Link's Awakening).
After spending some time with it, I have it as no less than the second-best* of the Zelda games straight up, IMO, at least until Breath of the Wild comes out and fixes all of the problems that the original LoZ has simply by being thirty years younger (less obtuse hints as to where to go, better items system, etc.).
I don't like Zelda II's combat (it's more fluid and intuitive in 3D to me, which is why I enjoy Dark Souls but not Zelda II), and really, Zelda II is all about the combat.
I enjoy modern (i.e. OoT - SS) 3D Zelda well enough, but I think the stuff outside of the dungeons very often is flat-out boring. Majora's Mask is an exception - that game is excellent because the stuff you're doing outside of the dungeons as you try to make sure everything goes right on your next run through is compelling. Every other game in this grouping, though, I personally think have huge dead spots where playing the game is like pulling teeth.
Weirdly, I should like LttP, but that never clicked with me on multiple plays. I ground through it once, but for whatever reason that I can't put my finger on, it doesn't grab me.
*I like Link's Awakening about as much as LoZ and for a lot of the same reasons, but LA's narrative conceit of Link being trapped in a dream world is one that I'm a sucker for, so it's probably still my favorite game in the series.