I'm not a huge fan of Mako. I liked him (kinda, sorta) in the beginning, but after the Spirit of the Competition, it was all downhill. I could rant about him, but other people have done that (and I love them) and I'm afraid I'm going to be yelled at rolleyes
I agree with the reasons people listed: Yes, he acted like a douche in the Love Triangle arc, leading Asami on when he obviously likes LOVES Korra. He doesn't receive any retribution for his actions, scolded Bolin for trying to date a teammate when he himself just kissed the aforementioned teammate, and went crazy when Korra was kidnapped. That was probably when I started to dislike him. How he acted during the search was totally out of the blue! He didnt act that way for his own BROTHER when he was also kinapped! What the hell?! scream
So at the moment, I'm pissed at him. Still, that doesn't mean I want him to be written out ENTIRELY. Just have him be forever alone in the end! Maybe once he gets some actual development, I'll start to like him again. Maybe neutral