I hated different characters at different points but most had redemption at some point. Mat and Nynaeve probably the most. Mat became my favorite character. 

The person who draws so much venom that I cannot understand is Egwene. There were certainly parts where she was a pain in the ass to Rand for really no reason but the same can be said about nearly every female character in the book. The other funny thing is most of the people who hate Egwene the most seem to love Nynaeve who as a character has a lot of the same flaws. Next to Rand nobody went through more personal trial and torture than Egwene. She was trained and beaten by the Aiel, collared by the Seanchan, captured and beaten by the reds. So when she pushed others I really didn't have an issue with it because she seemed to live by the mantra never ask another to do that which you would not. Finally anybody who sacrifices as she did at the last battle for the overall good to take Tiem and the Sharen channelers out to save others. 

Rather than a specific character the part of the book I hated the most was when Nynaeve and Elayne are traveling with Valan Luca. It seemed to last forever with no real purpose. The part with Mat was actually great with the interaction of Tuon and Joline driving him nuts.   

Funny but I didn't love Mat the first half of the series but the second half I never wanted his chapters to end. His interactions with Tuon and Talmanes were awesome. Of all of his one liners of which many deserve consideration I think the one I laughed at the loudest was the end of the meeting between Rand, Tuon and Matt when he says (paraphrasing) "Oh by the way I saved Morraine so suck on that while you're keeping score."