Captain James T. Kirk's least favorite word of all time was 'hero'.
For as long as he could remember, he'd been either "George Kirk's son" or "the son of the hero who saved the Kelvin's crew". Until he was 22, he was never just Jim Kirk. No matter how much he tried to distance himself from the incredibly large and suffocating shadow of a man he'd never met—by being a rebel, by getting in trouble, by not going to college even though he was the smartest in his grade of 500 kids—he was always the "hero's son".
He was ten when he finally snapped—when he realized that Jim Kirk didn't exist, partially because he was (incredibly unfortunately) the freaking mirror image of his dead father, and partially because he acted exactly like his dead father had. Perfect grades, perfect attitude, perfect lifestyle. Heck, once or twice his mom had even called him George, which, although it didn't seem like much, weighed in much more heavily since she was in deep-space nine months out of the year. But when he realized that no one saw him for anything other than a ghost…that it didn't matter how well he did in school or how much faster than his classmates he could run or how much better than Sam he could play chess…because his dad was the apotheosis of a man, in everyone's eyes… he quit trying to be perfect enough for everyone to see him. It was a fruitless endeavor.
This was a rather unfortunate realization for one cherry-red 1965 Chevy Stingray, as it became a rather effective outlet for Jim to scream to the world that he wasn't George-Perfect-Kirk (even though it did result in the car being smashed to pieces and burning at the bottom of a quarry).
Jim wanted to be a person. And the one preventing him from doing that was the hero who, although his sacrifice was something Jim admired, had forever tinted the screen through which everyone else viewed him.
So Jim decided he didn't like being the son of a hero.
Then there was the whole episode with Nero and the Narada and the small incident of him saving the entire planet, and for the first time in his life, he wasn't "the son of the hero"—he was "the hero". And that was even worse. All of the effort he had put into destroying his perfect-complex from his childhood, the one that practically made him George Kirk in everyone's minds, was back, completely unbidden. And while it was a relief to have his criminal record dropped like it was smoking hot, everything else seemed to go with it—his playboyness, his wit, his roguish charm. Suddenly he was a humble farm boy from Iowa (according to the media) who had daringly decided to save his captain, and the Earth, without any prompting from his superiors. There was definitely some "heroism must be genetic" stuff, but shockingly little. He may have hated standing in a hero's shadow, but he abhorred being the hero himself.
Jim Kirk's least favorite word was definitely hero.
Jim Kirk's favorite word was 'Captain'.
Partly because no one ever called George Kirk 'Captain', because technically he'd only been Acting Captain for twelve minutes. And when he'd finally found a family and a home that felt like a family and a home, he was greeted every morning with "Keptin on ze bwidge!", and "Good morning, Captain", and just the polite "Captain". Everyone he had grown to love since his stowing away on the Enterprise called him 'Captain' (or 'Keptin' or 'Kaptin', if you were Russian or Scottish). Captain was respect, love, family, and responsibility. Captain was his own identity, not his father's, or his mother's, or his brother's. 'Captain' was him. As soon as he was 'Captain', he wasn't the son of the hero. He was his own person.
Jim Kirk's favorite word was definitely 'Captain'.