Like everyone here I'm a film shooter at heart, so with that film-camera / digital-camera choice already made I guess I choose my modern EOS-1v for the same reasons a "modern" digital shooter would use their digital SLR. That is, when I need auto-everything it's my camera of choice. For example I love candid portraits, so when shooting my little kids I can capture more fleeting moments and get heaps more keepers with the EOS-1v thanks to its auto focus, auto exposure, etc, than I would with my older classics. Same with shooting candids of drivers and teams in the pits at motorsport events, which is another passion of mine. In other words, these modern cameras are great tools for reliability (regarding exposure, focus, etc) in spontaneous situations. Other factors such as the availability of brand new lenses, etc, are a plus too.
For my other more slow-paced shooting I do much prefer the enjoyment I get from my Pentax Spotmatic, my Mamiya C330F and my Wollensak Stereo 10. The EOS-1v is a high quality tool; the classics are a passion.