I'm on Cachy myself, but I have put in a lot of time with vanilla Arch. Cachy has an easier installation process, although the archinstall script is also quite simple to use. Cachy takes better advantage of your specific hardware, so it's good for squeezing a bit more performance out of your machine. Arch is more bare-bones, the idea being that you get to and have to customize it yourself, from near the ground up. It's a matter of use case and temperament, really. Both are good, and the differences aren't huge in the end.