+ AA6YQ comments below
I am an Icom fanboy and I will be the first to say that the company
+ Icom is better at documenting its CAT commands than most. Recall that I had to write the initial documentation for the Flex Signature's ethernet API by asking questions of Flex engineers.
+ Until recently, I would have said that Yaesu is the worst at it - but then I encountered Thetis, which is unbelievable poor.
+ Recall the FT-817/857/897 disaster, in which an undocumented command that writes to non-volatile memory addresses was used to modify radio parameters not accessible via the documented CAT command set. One logging application took advantage of this, ignoring the point that non-volatile memories have a finite "write budget". Exceed that budget, and the memory stops working, which bricks the radio. Evidently, Yaesu no longer has access to replacement parts, so those radios are not reparable.