I mainly had a video game context in mind when I came up with this question.
I thought about the topic from the Peri discussion that took place a page ago, as she would qualify for a character one could consider terribly written/portrayed to the point that person would hate her. Then, I remembered one major criticism against the Birthright characters that many FE fans emphasize: that most of the Birthright cast is "bland." It reminded me of discussions I've seen on Serenes Forest where, in a comparison between two characters, some people picked Peri over Kagero, Peri's Hoshidan counterpart who is commonly criticized for being bland, because they simply do not like bland characters and often usedthe argument, "At least I remember something out of Peri, unlike Kagero."
The Hinoka vs Camilla could also apply to this debate as well. One character is commonly criticized for being bland and forgettable but not very controversial (Hinoka), the other is commonly criticized for being a terribly written character and very controversial (Camilla). You could imagine why some people will pick Camilla over Hinoka or the other way around.
Then the distinction in this case would be that Hinoka is a more likable character, while Camilla is a more interesting character.
Personally, I actually quite like Hinoka as a character. She acts like an actual big sister to Corrin, and while she does have a bit of a tragic backstory element that makes abandoning her for Nohr more painful, they generally don't do anything too ambitious with her character. That's fine though, and overall, she's more defined by her interests and her smaller flaws (like her inability to cook) than some complex character that might only work in a specific context. She also has a sense of development (if you invite her to your room, she'll say things like "It's great to see how much you've matured", which indicates she's growing more accustomed to Corrin's presence and doesn't feel a need to be as over-protective of him/her. She also doesn't come off as overbearing in the Birthright campaign, and is surprisingly calm throughout most of Conquest, even though you can tell she's hurting). Overall, she isn't too deep or complex, nor does she introduce anything groundbreaking to the lore of the game, but I think calling her bland is selling her short, since she has an actually fleshed out personality, background, and set of interests, and also undergoes character development.
Camilla, by comparison, is actually pretty one-note in her personality - despite being the big sister in Nohr, it's evident they were really just trying to fill in the doting MILF archetype that's actually quite popular in Japan/anime circles (makes sense that they would want to do this given that the game has a marriage mechanic. It sounds silly, but they probably tried to fill as many "waifu/husbando" archetypes as possible because of the marriage mechanic). She is defined by this state of being in almost all of her interactions, sometimes with a yandere touch thrown in, rarely ever seeing anything that could be defined as development. What makes people say she is interesting however, is mostly her backstory and the odd touch of something different she gets in occasional supports. Her backstory in particular gives great insight into some of King Garon's deeds and some of the political workings of Nohr. Which is a lot more than what we get from Hinoka's backstory.
For me, I think Hinoka is a more interesting character/person, while Camilla isn't really that interesting at all, but she's written into situations that are really interesting which might fool some people into thinking Camilla herself is interesting.
Also I generally disagree with the notion that Hoshido has a more bland cast. I think Nohr's problem for me has been that characters are bland, badly written, or both, with only a few exceptions. Hoshido has some characters that don't do much for me but none of them really bother me (except for maybe Sakura), and the ones I do take a liking to (Takumi, Rinkah, Kaze, Ryoma, etc), are either super appealing (Ryoma isn't particularly interesting I'll admit but man, the guy exudes Rule of Cool, it's hard not to like him), really interesting, or both.
(Which is more orange in color than gold, maybe calling him the Orange Pilot would have been pretty silly?
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