In my opinion;
Perhaps if Sony had programed the A100's processor (or whatever) to reduce, or removethe chromanoise from the CCD altogether (Just as the Nikon D80 did with the chroma noises), I think it will stand a higher chance to be more appealing to the average users. (I meant people overall) Anyway, there is always post processing to do.
The O.P. can choose the K10D as most people might suggest in here.
If you think Sony could have reduced the noise in their camera to look better than the XTi and D80, then you should write to them and ask them why they didn't
I think a lot of people are recommending the K10D because it looks really good on paper. But, until it is released and people start using it (or reviews are posted), there is no way to compare camera functionality and image qualitybetween the cameras.