Mipha is dead. Good luck boning a ghost fish vag. Zelly is conflicted as feck; I read her diary and she suffers from that 'teen drama stuff.' You know: dead mother, disappointed father, trying to get into Yale, but you're stuck in community college, powers that only work when your life depends on it, and she hasn't found out about masturbation yet. Plus, that ass. Best Zelda ass of them all.
At first, yeah, agreed, Zelly is a piece of shit. You do your job and she treats you like crap. I thought about leaving her sweet ass in the castle more and more after each cut scene, but after reading the diary of the King, as well as Zelly's, I felt like she needed someone to love her. Someone to feed her cheese and pour some wine, sitting closely on a comfortable couch during the rain and lightning.
Mipha couldn't even defeat the easiest of the elemental blights. On top of that, she's only the princess of the Zora domain, which she'd never rule over. Logically, Zelly is still alive, so with her father being dead, Hyrule would have a new Queen. You'd have the best chance of marrying her, so ultimately, you'd be the new King. Best trophy for saving the world. And that Zelda ass.