Don't forget that Onpu's Zelda got 33rd at UJM too, not as respectable as Gungnir's amazing performance, but far from worth overlooking. Zelda also has better past results for the most part largely thanks to Ven (wins on K9, Zenyou, Vash, 65th at Civil War, 33rd at Mexico Saga, 4th at MSM 74, 9th at Rise 2017) and Purple Guy's efforts (wins on Dath, DJ Jack, True Blue, Xaltis, 8BitMan, has won a VSGC weekly with Zelda and got 2nd at the last one he went to before parenthood).
That said, my opinion's constantly changing on which is better. I think Ganondorf is more immediately threatening and has a stronger neutral against most characters because of that threat of all of his moves along with some safe, powerful options with good spacing like b-air, u-air and f-tilt, but Zelda does have Naryu's to give her some nice utility, a threatening grab game, and a much better recovery. They're both bottom tier, maybe bottom of low tier at max potential, but they've also both shown to require some kind of respect despite being at the bottom of the barrel viability-wise.