I know the basics of php but I would like to learn much more.
What's the best website/way in your opinion to do this?

I'd recommend learning laravel from laracasts

www.python.org

(You'll thank me later)

I always thought that once you knew the basics of PHP, it was time to move on to a server side language that was actually planned out and designed instead of being built on the fly by someone looking to make a blog and not trying to create a real language. (Actual origin story, btw.)

Laracasts