Ask HN: What coding challenge sites should I try next?

I'm learning PHP for a new position and tried using codewars and codefights. I'm not impressed by the UX with either of them, they're over gamified. The quality of Kata on codewars is not good (at least the easy stuff) and both are broken in random trivial places.

Can you offer suggestions on similar platforms that are less gamified, higher quality challenges, and more reliable?