For overrated, I'm probably going to go for the group consensus and say Ocarina of Time. I know I do rant about this game a lot, but I will say that I do still really like it. I just don't consider it to be the best game ever made, let alone the best Zelda. In some ways, its a bit like FFIV to me objectively. It did a lot for the Zelda franchise, but in the long run, it's one of the more vanilla entries in the series in terms of design and content. It has not aged very well, but thankfully the 3DS remake fixed a lot of the technical issues like the spotty Z-targeting, and an enhanced gyroscope to make using the bow significantly easier. I still feel that most of the boss fights in the game are still pretty fun.

For underrated, I have a few. I'd probably third Skyward Sword which I do feel is a flawed but still pretty fun game. I honestly don't even feel like the motion controls are the issue here for me, I feel it really was just making sword combat too much of a focus, as I feel it severely limited the creativity of the bosses and enemies found in the game, as well as undermining most of the special tools. It recycled too many bosses for me and I feel the game might be the worst offender in terms of dragging out stuff. With that said, when SS shines, it really shines well.

Another choice would be Spirit Tracks, which gets even overshadowed by its DS prequel Phantom Hourglass. While its over-world and side-quests are underwhelming, especially coming off Wind Waker and PH, not to mention the game is pathetically easy; it has more interesting puzzles to solve, a better recurring Tower Dungeon, and it may be one of the funniest entries in the series. It also allows Zelda to be playable and she's honestly one of the best incarnations of the character I feel I've seen in the series.

My third choice for underrated is Four Sword Adventures, which took the interesting, if terribly executed idea from the Four Swords mini-game that came with the GBA port of LttP, and actually made a pretty damn fun party game out of it. While a single player playthrough is not exactly ideal, if you can actually manage to get a full team playing this game, it's actually a real blast. It also has a better plot than Four Swords.

Also I found this amusing video and was curious to hear what everyone's take is on this.