I'm gonna go with Daisy because they've been advertising her a lot only for her to play a role twice (even the finale she just gets a cameo with characters like Gladstone despide Donald leaving with her being a huge deal). We don't even get to see her interact with Donald's family.
I think there should be more foreshadowing about her true loyalties (like when she hesitates to hurt Dewey and Webby) but aside from that, I think they did her character justice.
