Well, it is true that Nikon uses the same sensor as Sony (well at least in the D3x) but see the image comparison, Sony noise at higher ISO is the worst of the bunch, all blotchy, lose of details, high level of chromatic and luminance noise. So even if Sony uses the same sensor as Nikon, their image quality still suck at higher ISO so there must be something else. Like how the camera process the image?
All those tests are taken using the default settings, and who buys such an advanced camera to use everything at default settings?
On the default setting, the D300 produces horrible skin tones. There must be over 50 threads at DPReview's forums just on how horrible the default settings are, and how "consumer friendly" the colours and saturation levels are. Does my camera suck? No. Using what other photographers have noticed, I created 4 presets to give me exactly what I want in 4 different shooting situations, and none of them are remotely close to the default.
So yes, my D300 produces excellent JPEGs, and so does the A700.
Another point to be taken is ergonomics, most ppl end up bragging Nikon is better then Canon or Canon better then Sony partly come from their experience in ergonomics, I frankly cannot be on Sony side even its true that their camera offers value for money cause I HATE its ergonomics, so that totally rules thing out. I'm okay with Nikon and Canon ergonomics. (well I guess I don't need to tell that I hate Sony high ISO performance too)
Sony's ergonomics are great. In fact, it's one thing Minolta, and now Sony, was really famous for. This is particularly true of the Minolta 7D.
What's funny is you brought up Sony's ergonomics as not being good, because if there's one company that is NOT known for their ergonomics, it's Canon.
Also, frankly speaking, most 3rd party lenses is not as good as the lenses produced by the camera body manufacturer and I kept hearing horror stories about 3rd party lenses always have problems here and there and need to be returned, there are good 3rd party lenses out there just we must keep an eye about the problems we might face I guess.
First, that sounds like you have no idea about 3rd party lenses whatsoever. You 'heard'? There are lots of Sigma, Tamron, and Tokina lenses that are as good or better than Canon lenses. Sorry to be the bearer of bad news.