The answer to this question is rather subjective. If you are just starting WebDev and need a fast stable OS to help you achieve that, I would suggest going ahead with Ubuntu. Out of all the Linux Distros which I have used in the past, learning Ubuntu was the easiest.
The community backing Ubuntu is pretty huge and you will easily find answers to all your Ubuntu based problems. Its LTS versions remain in support for 5 years and provide the stability of a fixed release.
But that doesn't mean that any other OS will leave you unproductive. As I said, it is subjective. I used to be a huge fan of Linux Mint at one point, and it works like a breeze too.
Then over a year ago, I shifted back to Windows 10 just because my SSD made it a beauty and Microsoft giving support for Ubuntu bash made Ubuntu itself irrelevant for me. :)
I am using a MacBook Pro now :P