Is Kali Linux better than Ubuntu?

Any Operating System is better depending on how it's users want their systems to be. Kali Linux is Better? Yes and No both. 

Why Yes? If you're an inspiring Ethical Hacker or a budding Penetration Tester then having an Offensive distro with most infosec tools definitely gives you an edge over regular Linux operating systems like Ubuntu or Fedora or CentOS. However, it should be noted here that you can turn any Linux distro into your own version of Kali. You just have to install a base operating system say, Ubuntu and then install all the tools that are shipped with Kali, manually into Ubuntu or if you're good with Bash Scripting you may write a script that will do this for you. There are many such scripts available like this on Github. With that being said, there is a distro named Blackbuntu which is built over Ubuntu and is a similar Offensive Distro just like Kali Linux. 

Why No? Kali Linux might be an overkill for someone who is not into security but more into development occupying unnecessary space and a huge menu of infosec tools. It might only serve to confuse someone. Any Linux OS is shipped with some command line tools which are generally used during the process of infosec assessment, hence, everybody developer with some Linux knowledge should be able to learn them easily and implement security on their system or quickly perform some incident response. 

I hope my answer helped you out. If you need more info just message or call me or contact me or mail me. And yes, I give training in all the topics or areas discussed here namely, Ethical Hacking with Kali Linux, Linux for Beginners, Bash Scripting, Programming, and Advanced Security Training.