I like the arrays, they make it feel like a bit of a low level language and there are some weird tricks one can do with them. As for class property behaviour, I kind of get nervous if my properties or the constructor don't enforce default values I can then fit into downstream logic.

One of the best things with PHP is PsySH, or "Tinker" as the laravelists call it. It's not a REPL in the Common Lisp sense, but it is quite nice for an interactive programming shell. I've spent countless hours solving problems very, very quickly in it, and alongside Picolisp pil + and Elixir iex it's one of the earliest tools I install on a new system.

https://psysh.org/

The thing I miss the most is a nice concurrency story. It has become better but it's still a bit of a mess, often it's nicest to just implement workers as PHP and then implement control somewhere else, e.g. Elixir, or grab one of the application servers that are nowadays a thing in PHP.