Really hard one this.
Depending on how the question is phrased I could choose either.
OoT is obviously the defining moment in Zelda games. The blueprint for certainly the 3D games, which I much prefer over the 2D or 2.5D iterations.
A truly ground breaking game that at the time of launch blew minds.
On the other hand TP I feel is the definitive Zelda experience. If someone had never played a Zelda before and wanted to know what they are about TPHD would be my recommendation. It does everything OoT does but for the most part improves upon it.
Better graphics, better controls if avoiding waggle, better dungeon design.
The competition is "Best Zelda game", TP is better than OoT in so many ways that it has to get my vote. If it was favourite, or best memories, or most important then OoT might get a look in.
TPHD is better than OoT.