The EOS 1 was the first of the pro EOS range and still a good camera, but looking a bit dated now, as they could be anything up to about 20 years old, and I'm pretty sure there's only one central AF spot. A lot of them will have been well hammered by pros too. The EOS 3 came along much later
I faced the same choice a while back and I think if you're looking for a really good quality body it comes down to the EOS 3 or the 1V.
I opted for the EOS 3, it's a a really well built camera, the eye focus actually works well as long as you're not a specs wearer, in which case you're better off switching it off. It has 45 auto focus points, a fast AF system, is compatible with all your EF lenses, does 4 fps (7fps with the optional power booster) and feels very much like a 1 Series digital camera in it's overall concept. If you've used a 1 Series Canon digital camera, you'll be very much at home with the EOS 3.
The only slight niggle for me is that there's no eyesight diopter adjustment in the viewfinder,(due to the eye sensor taking up the space presumably) so if you're a specs wearer, you'll have to wear your specs, although you can get eyesight correction lenses.
I've no intention of parting with my EOS 3 - it's the dog's wotsits - get a nice one and you've got a camera for life.