No, Abby is the best character of the moment, because she is interesting. I don't like her either, but I can clearly see her story, her inner struggle, her flaws and what she is trying to do. I can't really do that with most main characters. Bellamy, Clarke, Octavia, Indra, Raven, they just fight with each other for a throne. Sometimes one side has the upper hand, sometimes another. That's just boring. What's interesting are characters with plans and convictions, like Monty, Kane, probably even Dioza and McCreary (though here it could be that it's the first time we are seeing them fight and scheme).
They kinda botched the 6-year jump. While relations have changed, they tried to introduce mysteries in not telling us how. Mentioning the dark year over and over again without us knowing what it is is faux suspense. It's a trick. They'll get a big reveal, but probably on a rewatch we will be asking ourselves "why?" and "that doesn't make sense". And the repetition will get on our nerves more than it already does... And I don't think the characters have changed all that much in 6 years. They should have learned a lot, instead they seem to do the same mistakes as before, just in different constellations of who likes who... That's not real character growth.