@Anonycat
Comics however feature an
entirely different Luna than the one we see in the series,
especially the one from Katie Cook (which excels at Slice of Life and making everything silly) and Andy Price (which art style heavily weights towards parody and exaggerated expressions). One has a pet possum and couldn’t remain serious even if her life depended on it while the other never misses any opportunity to claim how misunderstood she is by the other ponies and how she’s
crawling in her skin at the thought of the
horrible evil she did as Nightmare Moon to the point of masochism.
As for Celestia, the Spike/Celestia comic featured some well-deserved character development for her, bringing up the whole “Don’t directly tutor your student but watch them from afar so they grow by themselves” ordeal
years before the series did. It was of course ignored, as is the vast majority of comics, for better or worse.
When it comes to “Emo Teenager Princess Luna”, though, the fact remains that any episode she’s in will have boundless praise due to her target audience. That’s just a fact. When it comes to Celestia, though, she’s the one hard to relate with, the 1000+ years old ruler that’s seen
a lot, yet is almost always mistreated by writers into being passive and useless, sitting on her pile of life experiences and never using them, or wanting to try something new like she did in S1’s Best Night Ever, one of the rare gems of character development for her. That’s going to take a
lot of effort to fix.
TL:DR: The easier someone relates to a character and the more character development they have towards said relation, the more they tend to be loved. Luna has both, Celestia has
neither. Being able to relate to someone is
everything.