Nobody answered the question
As nobody really answered the question I suppose I could try to give a reply which is un-biased. Of course I do shoot Nikon. Just sticking to the best features of each camera :
Nikon D80
- great viewfinder
- great flash system
- excellent autofocus and exposure system (though exposure is less accurate than D200 & D2X)
- wide choice of excellent lenses designed for digital
- manufacturer committed to the sensor format
- same SD card format as your Canon S3 IS
Canon XTi
- cheapest of the three
- dust-removal system for the sensor
- light and small (if you happen to have small hands)
Canon 30D
- better low-light performance than the other two
- 5 frames per second
- low-level pro camera
I find it very difficult to work up any enthusiasm for Canon, somehow..
Feel like I'm talking to myself here
No sign of life from the poster or even from a Canon Champion. Feel like I'm talking to myself.
Anyway - I've thought of another advantage of the D80: Auto-ISO. You set the base sensitivity and the longest shutter speed you want and if there isn't enough light then the camera changes the ISO setting by itself. It's really useful and Canon don't even offer it.
Right now with my D200 90% of the time I'm on auto-ISO and 95% of the time I've got the 18-200VR fitted and Canon don't offer either.