It took a ♥♥♥♥ing eternity to load that PDF you linked to so here's some image links.
Link Midna
I find the imp form prototypes a lot more interesting. Midna went through some pretty ♥♥♥♥ed up prototype stages and, honestly, a more monstrous imp form would have REALLY helped with the feel of her development. The one she ended up with seems too cute (if oddly sexualized for the toddler-like proportions) and in the beginning it seemed like they were trying to make her seem threatening, which didn't work, and she was afraid to let her people see her in imp form so it should be ugly in addition to somewhat monstrous.
Also, almost every other image for Link (in the Hero's Clothes) looks better than the one they ended up with. Older looks striking and fits the feel of the game, younger fits his personality better, LttP style would have been a cool throwback, and the Japanese one with the heavy shading looks way cool. Better to go full Japanese facially than white with some light hints of Japanese that you can feel but not really put your finger on, like they ended up with.
And a low-poly black wolf form would have better fit the Twili magic aesthetic.
THANK GOD they didn't go with that third Zora Armor but we missed out not getting that glowy one.