I read so many reviews, tweets, etc about 'likable' characters. You know how they say publishing is so subjective. well, so is reading. And with that said, liking characters is too. There are characters I adore that others hate, there are characters others hate that others adore. At the end of the day it doesn't matter if people don't like your characters as long as you wrote them true to themselves. Not every character I like is the same, some are quiet, some are loud, some are tall, some are short. They're just like people, we don't like everyone we meet right away, it can take time. Or maybe we won't ever like them, but as long as they're real, that's what matters.
The one thing characters I like have in common? They survive. A character who is strong doesn't necessarily go out there and kick someone's butt. Sometimes they even stand back and are quiet in the face of adversity, but along the way they grow and become themselves. That's what I love about reading, watching the journey of someone I may not like as they evolve. Make sure your character is learning, is growing, is true.