Favorites:
1.) Midna, because she's the only person with character development done perfectly.
2.) Groose, because of comedy gold and character development.
3.) Ciela, because she's the only fairy that isn't annoying.
4/Bonus.) Agitha, the only girl in hyrule who won't cry "Monster" when Link's is a wolf, but you have to get past her addiction to bugs.
Least Favorite:
1.) Tatl, yes she is more annoying than Navi and that's not taking the 3DS remakes into account. We have less than three days left and you want to talk!
2.) Navi, okay I think I know what a vine looks like. Why don't take page from Midna's book and let me figure it out on my own. No wonder people had trouble with the water temple, they're so used to taking baby-steps from you.
3.) Fi, most bland character in zelda. Suffers from the same problems as Tatl. The only redeeming quality is she never attacked Link unlike Tatl <evil glare>.
4/Bonus.) Linebeck, a complete coward who is completely full of himself. "I sprained my leg," -Linebeck. Yeah right, let me tell you my life story Linebeck: when I was seven, I had dream I could fly. The next day I jumped off the highest pole on the playground. I sprained my right leg. Since then, I've think I've been cursed because I've sprained myself every two years since. I'm past due for next sprain now that I think about it.
Sorry for ranting.