The good thing about Wayland is that security is much better. In X, a compromised application can easily steal information. Sandboxing is hard. The bad thing about Wayland is that changes to the architecture are incompatible with window managers, which require a rewrite.

Things like XMonad or StumpWM are relatively popular among Arch users so that is why X is still featured prominently in the Wiki. I use those two, but on NixOS, and I find it annoying there is no simple migration route. Waymonad never took off. StumpWM/Mahogany seems to be getting there, but AFAIK there is no release in the horizon yet.