As Dean has already stated, “As far as which camera to choose? A lot of it comes down to personal preference.” Between the D90 and the A700 this may be especially true because the image wise there isn’t a lot to distinguish the two cameras from each other. That means it comes down to features and ergonomics, and if you go handle the two cameras and shoot some with both cameras you should quickly be able to decide which one “fits” you best.
Both cameras have a Sony built 12MP CMOS sensor, although they differ somewhat in the picture dimensions, and for all practical purposes may be the same sensor. The Sony version is 4288x2856 (Raw L) vs. Nikon’s 2488x2848 (Raw L) and 4272x2848 (Jpeg L) vs. Nikon’s 2488x2848 (Jpeg L). A difference that is insignificant to say the least, but also sort of curious. In the A700 review when compared against the D300 (jpeg) the two cameras were practically the same and Phil stated,
“The DSLR-A700 and D300 have identical vertical pixel count, the only difference being the D300's 16 extra horizontal columns (obviously Nikon has a slightly different interpretation of 3:2). A quick scan down these crops indicates that there's very little difference in absolute image quality apart from perhaps slightly more low contrast ('texture') detail from the D300 and a very slightly more conservative approach to sharpening.”
For the Raw comparison Phil concluded,
“Using a RAW conversion workflow there really is almost no difference between the DSLR-A700 and the Nikon D300, not hugely surprising as we suspect they share the same sensor (or at least very similar).”
In 2002 I had a Sony F717 (still have it), which was one of the “Hot” Prosumer cameras at the time. When I upgraded to DSLR (D50) Sony hadn’t yet come out with a DSLR. I have looked at Sony and I’m not sorry that I went down the Nikon path. I don’t like how the Sony feels and handles anywhere near as well as I like the Nikon experience. I also don’t care a whole lot for the lens selection. People talk about how you have to pay for VR every time you buy a lens but only once with Sony – when you buy the body. Well if you look at the price of the lenses that argument doesn’t fly. Besides Phil has stated the Sony only yield 1 to 1.5 stops, while Nikon get 3 to 4 stops with VR.
Read the A700 reviews Conclusion page and decide if any of the Cons are deal breakers for you, or if any of the Pros make the A700 a better fit for you.
http://www.dpreview.com/reviews/sonydslra700/page32.asp
I look forward to dpreview’s reviews; I didn’t need it this time to decide that the D90 was the right camera to replace my D50. I knew the IQ would rival the D300’s, and I could read the specs and the early reviews to see what features the D90 had or didn’t have. With but a few exceptions the D90 had all the features of my wish list, and those missing all fell into the “nice to have” rather than the “have to have” category. But my wants and needs may be quite different from your wants and needs, or even Phil's likes and dislikes.
Again, go handle both cameras and see which one fits your needs and wants; you aren’t going to be able to look at a picture and tell which model the picture came from.
--
Brooks
http://bmiddleton.smugmug.com/ 
