She was manipulative, a compulsive liar, a racist, and somewhat genocidal.
This was Azula

. Kuvira was just simply very goal-oriented in a "the ends justify the means" way. She pushed for success, but she had her people's best interest in mind all the time. She didn't do this because she liked it, but because she had to. In this way, she forged the poor and weak Earth Kingdom into the powerful and prospering Earth Empire. As it was once mentioned, she was a person who could accept "hard truths" and invoke anti-hero tropes instead of even trying to be a spotless person. Korra was pretty much her exact opposite in this manner.
Yeah, I see what you're saying. But here's the thing:
1)
Kuvira and Azula are not as different as you might think. Kuvira may have been more well-meaning than Azula, but there were many similarities in their methods. Like Azula, Kuvira consistently threatened her subordinates and used fear to control them. Like Azula, she oppressed people who weren't the same nationality as her own (the biggest example would be her purging and imprisoning people who weren't historically native to the Earth Kingdom). Like Azula, she lied and manipulated her officers, allies, and her followers on a consistent basis (such as Bolin, Korra, Varrick, and even Su to an extent). Even their backgrounds have similarities as both of their more villainous qualities stem from parental abandonment issues. However, yes, Kuvira is a much more emotionally stable and moral character than Azula. This brings me to my next point.
2)
Kuvira is an anti-villain, not an anti-hero. Anti-villain: A character who can be considered more noble or heroic than an anti-hero, but the means to achieve their ends are often considered immoral, unjust, or evil. Unlike Azula who is totally a villain, Kuvira does have good intentions behind her more sinister qualities. She deeply cares about her country, she commends and praises her officers for doing well, and she tries to negotiate with political leaders before manipulating or threatening them. However, she's still extremely ruthless, abusive of other nationalities, exceptionally arrogant, and still qualifies as a monster.
3)
Korra is an anti-hero. Oddly enough, your opinion of Korra kind of validates this

.
Anti-hero: a central character in a story, movie, or drama who lacks conventional heroic attributes. Korra has a lot of issues as a character: she can be arrogant, spiteful, ruthless, mean, hot-tempered, and just downright cruel at times. She also makes plenty of questionable decisions throughout the show. HOWEVER, she's still the hero of the story. She wants to save the world. She wants to bring peace. She strives every day of her life to be a more caring and compassionate person. And she wants the people in her life to be happy.
Let's see... she ran away from the White Lotus
Ehh...not exactly. It was less of her running from the White Lotus and more her running
toward Republic City. She wanted to learn airbending, therefore she went after what she wanted. Basically, she did what an active protagonist is supposed to do.
she ran away from Amon, she ran away from Unalaq,
I don't think these count as her running away from her "problems". These are examples of her retreating from physical fights she simply couldn't win and regrouping with her allies. She retreated from Amon because she was tired, weak and spent nearly two days in a box. But later, she took him on directly. And IIRC she defeated Unalaq and left him in order to save her father.
she ran away from Raiko, she ran away from Unalaq again,
She wasn't running away from Raiko. But she was running away from Mako because he, you know, broke up with her. I guess this sort of counts, but its...kind of a natural reaction, don't you think? And once again, tactical retreat. She fought him and lost, so she came back with help.
she ran away from Raiko and RC,
Actually, she got kicked out. Raiko ordered her to leave. Not to mention, she wanted to find the other airbenders and that was way more important.
and finally she ran away from the whole world in a hope to run away from herself.
Yup, you're right about that one, Buddy

.