Agree with most of what you say Barry, I think after Fuji dropped the EXR feature after the X-10, Jpegs got worse, and I totally disagree with DPReview when they said the X-20 and later the X-30 was sharper and a lot better than the X-10, it simply was not in my view and the Jpegs were not as pleasing. I think they more or less got it right with the X-10 and its still a favourite of mine.
DPreviews said about the Sony A6000, that Sony had finally got some decent Jpeg output with a good balance between noise, sharpening and IQ. Hmm, not sure Sony are quite there yet, although the Jpegs look better and more balanced than my old A57/37 ever did.
However, Sony have still not grasped how useful user noise adjustment would be. The two adjustments available are a feeble nod in that direction but its only effective at higher ISO.
Agree about Nikon, the old D80 and D90 were excellent Jpeg cameras and the newer entry/enthusiast level D series seem quite good.
Not sure about Canon Jpegs, they are a law unto themselves but looked quite nice the last time I looked, a bit too much default sharpening may be.
I still think Olympus hold the Jpeg crown, but after they started using the Sony sensor in the M43 cameras, in my view the Jpegs are still good but nor as good as the older Panasonic sensors in the E series, Poor DR and high light clipping being the main problem along with limited high ISO were the down side of the Panny sensor.
This is where the Sony sensor has improved the Olympus M43 cameras, DR and high lights. Olympus is one of those few cameras where user adjustable noise reduction does work and you can see the effects each setting has.