Both Of This Are Well known Operating systems For Ethical Hacking and Penetration Testing. But Who Is the Best Well Probably Both of This Are Best
Parrot os is Best for User interface (But a hacker really need This Kind Of User interface) and also more Tools than Kali Linux.
kali Linux is the Powerfull operating system with all needed Tools
So what is your Choice attractive Parrot Or Dangerous dragon Of Kali?