My initial choice for a Zelda newcomer was always Impa because her importance to a number of games. However, if I had to pick any character from any Zelda game, it would be Skull Kid. Majora's Mask is my favorite Zelda; which is tied for my all time favorite series beside Metal Gear, tied for my favorite game of all time alongside Metal Gear Solid 4, and Skull Kid was my favorite character within that game. So you can imagine I was pretty happy he picked up traction this speculation period.
However, if we never got another Zelda rep, I'd be totally fine. I feel like the fighters we got now embody the series really well and Zelda is super well represented, almost overrepresented, in every other department in Smash. I mean Zelda got two new stages in nearly EVERY Smash game and ALL of them came back for Ultimate. 4 Assist Trophies, several items, and a **** tone of music. I'm pretty satisfied with Zelda's representation in Smash.