I may be going against the grain, but I prefer Prince Claudia to Yulan.
And I prefer him for the fact that he's not the classic perfect guy, protective and always with the right move at the right time; but in his view of the world distorted by his personal idea of justice he's full of flaws, he goes into crisis and is full of doubts, but in his own way he tries to improve himself and correct his mistakes without justifying himself (this can be seen much more in the novel, which has much more mature and dark tones than in the manga).
Claudia is an imperfect character and in his own unpleasant way, just as Violette is imperfect and unpleasant, but for this very reason they are much more human than almost all the other protagonists of similar stories.