A little late to the party here, but I'm surprised nobody's said anything about the lens' max aperture. Larger max aperture generally means brighter viewfinder. So if one lens is f/1.4 and the other is f/5.6 you're going to have a significant difference in viewfinder brightness. If you really want to compare, either get like-sized lenses, or stop down the larger lens to the smaller max aperture of the other. (There will likely be a noticeable difference between viewfinder design of the F2 and EOS 3; to be expected, considering the age difference.)
But if you're just fishing around for an excuse to get yourself a 1N... The 3 is a more advanced camera than the 1N. I have both, I like both. I used the 1N a month ago, the 3 has been sitting in a Crown Royal bag for at least a year. And I prefer my T90 to both of them.