I am completely new to Linux, but I am trying to learn how to pentest as my end goal with Linux. Which is the best distribution of Linux I should install?
There is no such thing as the best distribution of linux but you can definitely try any of them. I prefer to stick with Ubuntu or any other Debian OS.
well, pentesting is exactly what kali linux is designed for, it comes with most of what you'd need already installed. although most, if not all, of the packages it comes with should be available for any of the major linux variants. just a bit more hassle installing them rather than have them included. i've not used kali myself, but i've heard it isn't the easiest to start learning on though, i suspect they expect you to have a suitable amount of experience and competence with linux to begin with.