One is a popular web3 and eth scaling chain. Their tech is solid but i wont talk about it.
Harmony's eth bridge was hacked and they had to print 100m Usd worth One. This means if they get hack again they will keep printing ONE.
Also if you go harmony forums you will see someone is not happy about dev team's leader. One of Harmony's creator 'Stephen Tse' who is also leading almost everything, faceing being dictator. Community is not happy about that. If community is not happy this is a huge proble for project.
When you watch some vidoes on youtube which made by Stephen Thse he is acting so weird. I dont believe he can lead a project like ONE. Maybe he is a first class coder but marketing is something else.
I wanted became an investor BUT after research i will stay away. Be safe and remember DYOR :)