@Rhythmatic I love both, to be honest, but for now I'm avoiding to compare them because there are only 14 chapters of CtW out, and Ouro is already finished.
However, I do see positive changes in CtW that may make it even better than Ouro as it progresses. For example, Yuuya's art has reached maturity in CtW (though his backgrounds are sometimes off in terms of perspective, but that may be the fault of his assistants): characters in the first 30-40 chapters of Ouro were really ugly.
There's also the fact that Ouro relied a lot on episodic cases in the first half of the series. There was the whole plot with Gold Watch, but for around 70 chapters, it was just Ikuo solving unconnected cases. CtW, in contrast, has a central plot that takes front stage from the beginning.
So all in all, yes, CtW might rise to be Kanzaki's finest effort. Ouro was only his second series, after all, and it achieved a very high level of quality. But it's a little early to tell.
(By the way, Kanzaki's first series was never scanlated and ended at three volumes. I gave it some thought but gave up in the end. It's called
Subtropics nine, it's about baseball and - no kidding - it ran in
Weekly Shounen Jump! I'm glad Kanzaki moved to seinen and another publisher straightaway. Shueisha definitely didn't fit his style.)
Chapter 14 is typeset and at redrawing right now, so look forward to it soon.