I used Z80's back in the 1980's and used to have a bunch of them around, but with all the other processors now available, they are not something I would try to use today. Too many support chips needed.
Given the Cypress PSOC, I would start there instead.
The issue with using modern parts is that one needs a PC and also allows one to gloss over the fundamentals with everything provided on a platter.
Building a Z80 system forces one to at least assemble some hardware, learn machine code if desired, have many more hazards to navigate and develop a full sense of what is going on.
Here's a comparison of the different levels of programming learned.
