Ask HN: Best homebrew computer for noobs?

With the holidays coming up I'll have some free time for projects. I've always liked the idea of building a computer, even a very simple one, from scratch. What books/articles/kits out there does HN think are good for a first timer who not only wants to put something together, but also gain some understanding on how everything works?

I've seen the N8VEM/RetroBrew, RC2014 and cpuville Z80, are any of these good candidates? I'm not set on any specific CPU type, just something that is basic enough for me to understand how it all works but also a system that can do _something_, even if it's just basic loops or whatever.