D1x
it has less dr than the others but in softer light it has sweet rich colour, meters on manual focus lenses, has the strongest, fastest focus motor of anything (afs, who needs that) 1/500th flash sync and iso 125 if flash is your thing. iso 1600 is grainy but nice, in fact I find it more usable than the less grainy 20d often.
battery life is not the best but I used to do weddings on 1 and a half batteries, apparently there is a lithium conversion available now anyway.
I have a d100 also but I hardly ever use it, I have a d2x for my work but the d1x is my home and backup camera. for almost twice the price a d200 would be a better buy. D40 if you only want to use afs lenses or manual focus. Fuji s3 is a good buy too, would get that over a d100 or d70.
using a canon with nikon lenses is daft unless you only use wide open, yes they meter but the diaphram is manual stop down only, and you can get a nikon for around the same price anyway.
I use a helios 40 and a 55 1.2 S-C on my d1x.