I'd have to say Link's Crossbow Training was probably the most overrated Zelda game. I mean, have you seen it's sale statistics? It's sold more copies than every other Zelda game except for OoT, tLoZ, and TP.
Spinoffs aside, I'd have to go with TP or SS. They both were good, but neither great. A large argument on this forum is about which is better, and I say neither (although atm I'm kinda leaning TP, but that's besides the carefully laid out point). They both have their good parts, and both have their flaws. I just see them as good Zelda games, but many around ZD seem to love it intensly, or at least more than they deserve.