Instead of going for brand name, the very first requisite should be:
BE OBJECTIVE
Just want to share my experiences in deciding which system to go.
At first I almost fell into the 'function' trap did decide to go for D70.
Then I sat down, grabbed a piece of paper and pen and wrote down what I really needed and what I really like and dislike about both bodies.
Followings were my take:
1. I really like CMOS and it's silky smooth ISO100. Of course you can post process noisy photos with the likes of Neat Image. But then again, if you can get it out-of-the-box with no signal loss, why not?
2. I really like the green done by Canon processors and better red for Nikon. But I am more into macro, nature and landscapes. So...
3. Upon scrutinizing several times and comparing photos from both cameras in dpreview.com, I found several artefacts in D70 samples (of course only after some enlargement & I could be over critical here) and actually prefered images by 300D when compared side-by-side with D70 in Phil's example. Again, this is strictly personal taste.
4. On prints, Canon appeared to be 'print friendlier'. Perhaps images produced by Nikon were over sharpened in-camera. That could help a bit by reducing the sharpness level in Nikon system but overall, to my eyes, Canon still produces a more 'natural' look.
5. The functions in D70 was impressive. But with the hack, I have great fun with 300D. At least at this stage, although 300D may have less manual functions than D70, I still have a hell lot to experiment with and by the time I'm through with it, new generations of camera bodies are already out.
6. Lens prices for Canon are really hard to beat. Some might say it's not significant. But hey, even if it's $100 difference and the quality is comparable, it's a lot of difference!
7. D70 is black. Indeed. But I like the dark silver in 300D better.
8. 300D has cable release. Interestingly, this cable thingie looks unimportant but I use it very often so it's something I don't want to forego.
I could go on and on but what I am trying to say here (& don't want to start a flame war as some might want to suggest) is that no camera body is perfect.
It's how you find a solution to it.
Finally, if I don't mind the hasslement and piling dozens of lenses, I would have gone for both D70 & 300D because D70 is lightning fast & 300D has really nice green!
Just my 2 cents.