I'm guessing OOT, at least for the 3D Zelda's.
I personally started with ALBW, then LA, Hyrule Warriors, MC, OOT . I already am getting WW HD for xmas but I'll buy & finish MM 3D before I start WW. Then you guessed it, TP HD squeezed before Zelda U.
I shall play SS whenever there's a remake. I don't care for any more old 2D games.