Honestly? I couldn't tell you.
I mean, I have an complete set (game, box, manual, misc. pamphlets) of Uniracers, Equinox and the JP version of Chrono Trigger, GoldenEye 64 (Player's Choice), and a couple of the Dragon Quest remakes on the DS, but I don't think they're exceedingly rare or anything. Well, maybe the DQ games.
I'd probably need to have someone much nerdier than I to take a look and tell me which games I have that are super rare.