Upload & Sell: Off
I've owned and used (for a short period) the 1Ds and (extensively) the 5D (I assume you mean the mark I of both?); I've never used the 7D, so my comments are less applicable to that. But given the choice between the former two, I would not hesitate to recommend emphatically the 5D.
The 1Ds has usability issues resulting from it being an older camera. For example, you'll find that the time between capture and images appearing on the LCD, especially with bursts, is significant. We're talking 20+ seconds significant. You shoot a couple of shots, and then wait. Moreover, the LCD is smaller and of lower quality, so it's a lot harder to get a good sense of your images. The menus are more cumbersome to navigate (at least, in my subjective opinion).
Also, the max iso on the 1Ds is 1250, as opposed to 1600 on the 5D. (I think that both of them advertise an "H" iso, but that's just software). The resolution is lower, as well.
The 1Ds does have a couple of advantages: the shutter blackout is noticeably shorter (though the 5D's isn't bad), the AF is much more flexible and configurable, the viewfinder protrudes farther, and if I recall is closer to 100% coverage. Built-in grip may or may not be an advantage from your point of view, but it does feel sturdier than the 5D with attached grip.
I bought it cheap after already having the 5D for a while, and found that it didn't provide me much benefit, and ended up selling it. I realize that these criticisms sound vague (it's been a while!) but I think that if you were to try it out for a bit, you'd see what I mean.
If you do action shooting, you might want to consider the 7D. The AF system on the 5D is very lackluster, as the points other than the center don't track well. I believe (haven't checked) that the 7D offers microfocus adjustment, whereas the 5D sadly does not (perhaps it would have helped with the many backfocused shots from my 50mm f1.8 II). And the 5D's burst rate is not great.
But if you're interested in low ISO performance, 5D all the way. Performance is significantly better on the 5D than on the 7D (look at the ISO charts in the reviews on the-digital-picture.com). The 5D outperforms essentially any Canon crop released to date.
In short, I was extremely happy with my 5D. I recently sold it to trade up to the 6D, but it was and remains an excellent camera.