What's the ugliest human emotion?

jealousy/lustfulness and pride..... joy yess yess joy

Jealousy is the ugliest trait.

James 3: 16

"For where jealousy and selfish ambition exist, there will be disorder and every vile practice."

A loving heart is a the best trait any human can have.

Annoyance. That. Also uncertainty, but I think annoyance. To be honest, if there is one emotion that will turn anyone's day upside-down. I do think anger is pretty ugly, but I mean come on, give me a break, if you are annoyed at hatred, then you are experiencing annoyance. (Sorry) But I do agree joy is the most beautiful. There is a scientific sociological way of describing it, but I think that is too far for being a "personal experience" as you say.

Yes you are right but you can't leave out jealousy which can lead to Anger and Hate.

I would say greed. Greed motivates people to live entire lives that hurt others. Plus it is currently acceptable in our society. For instance, it is perfectly acceptable in our society to vote for Hillary Clinton because she promises to give you money from the government. Hate would be a close second, but hate is not as accepted in our society. Like the Klan was a hate based group but they have largely been minimized. Of course, if someone takes a position that is not popular, like say they just politely decline to attend a same-sex wedding, they would get hate directed their way - death threats, lawsuits, businesses shut down as we have seen. But that is not quite as damaging to our society as the greed we see.

Embarrassment sucks

Fear.

Fear leads to hate. Hate leads to anger.

Fear is the little mind killer.