First of all, I would not switch. Not for that lens. The 16-35 is not worth switching for. It is not that sharp, the ultra wide end of it is way too wide for me and not that useful for most things, and Nikon has an equivalent: the 17-35 f/2.8 ED.
Canon has the following that significantly set them apart from Nikon:
24mm 1.4
35mm 1.4 with AF
50mm 1.2 with AF (and 1.0 if you spend a lot and buy used)
85mm 1.2
45mm T/S
Used to be the 24mm T/S as well, but Nikon just introduced a competitor.
If you don't see yourself using any of those lenses, there is no point in switching, IMO.
Nikon has the 35 and the 50, but manual focus only.
Also, Nikon has things in other areas that Canon dos not have: most notably the 200-400, a much cheaper fast 85mm (albeit 1/2 stop slower than Canon's), and a much cheaper fast 200mm ($4,000 vs. $6,000 for the Canon).
Nikon have done little work on their fixed-length lenses during the AF age, compared to what they have done on their line of zooms. They seem to have put most of their work into designing zooms instead. As such, Canon beats them hands down in the very fast fixed-length lens department, while it could be argued, probably successfully, that Nikon beats Canon zoomwise.
Super teles from Nikon are more expensive than the Canons, however.
Either brand will get the job done just fine. It is just a hassle to switch. However, if you must, the EOS 3 on the used market is an unbelievable bang for the buck. I would say it is equal, if not superior to the F100. It has the same AF as the 1V, plus ECF, and is about half the price of the 1V. My friend got hers locally for $175, and it looks like new. Usually you can find them for $300 or less.
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