Opal was just so...I don't know. In the beginning she was too cute and bubbly, those characters tend to annoy me. But I still thought she was okay. However the way she treated Bo bothered me. I understand why she was mad and such but after a certain point she just held it out too long.
Su is just so hypocritical and biased it's not even funny. Before toi all start in on me with the 'omg u just hate her 'cuz she hates Kuvira!' No, not at all. I wasn't to fond of her right off the bat. Honestly I hated her plus on Lin's behalf in the beginning. There was just something I didn't like about her. And then I found it; she ran with criminals and then proceeded to leave her own sister scarred. plus over she killed P'Li. I liked P'Li. I do understand that it was in self defense, but I still don't have to like seeing a cool character die. And then there's what she did with Kuvira. As discussed in my article, Kuvira was asking her to help the Earth Kingdom. But she didn't and then got all pissy when Kuvira went for it. Let's also go back to how she was a criminal--yup Su was a criminal and she got a seconde chance. And she doesn't even try to understand Kuvira ou give her the seconde chance she got; Which is where I think the hypocrisy lies. As of the bias; "we'll get through this as a family" 'nuff said. And last but not least; if toi take a child in...if toi adopt a kid toi treat them like they are family, and toi don't cast them aside like their bio-parents. At least that's how I feel about adopting a kid.
And finally Mako. I don't even know where to begin with him. The way he treats his brother (kissing and stealing his girlfriend right in front of him), cheating on Asami for Korra and then cheating on Korra for Asami shortly after--granted Makorra was broken off at the time, but he kissed Asami and then when Korra came back he cheated on Asami again... (it's like make up your mind), the fact that he's so hot headed and arrogant. And above all (slipping my bias glasses on) he killed Ming Ming. I loved Ming Ming so much. Again, yes it was self-defense, but I still hate any character that kills my favori character. I just hate Mako with a passion.
This probably offended a few people. My apologies but I had to get it off my chest.
I'm really torn. I really hated Suyin and Opal, and I originally hated Mako so much. And Bo really got on my nerves to the point of me not liking his character. Same with the air family..... But I have to say, my least favori character of all time has got to be Korra. I didn't like her from the start, and her actions only made me dislike her more. And then par the finale, I was ready for this series to end. When the protagonist is not likable, the montrer lacks. That's what happened for me.