There seems to be a preference for a specific media or material. For example,
I like watercolor, don't like oil (I mean painting with it, I do like seeing
both types). There are certain things that watercolor can do easier than oil
or some effect that is almost impossible to do in it, and vice versa; but *I*
just like watercolor.
Acrylic color is available. One can dilute acrylic and get about the same
effect as watercolor. The feel while executing the painting is different
though, so *I* still prefer watercolor.
Then the techniques when you use different medium are also different. I find
that you can't say which one is best. It is mainly a preference (I mean,
especially if we are talking about artists; for commercial work, sometimes one
technique is clearly better than another in terms of cost effectiveness).
But as far as alt. photo is concerned, I think one main difference is the
final look. There is a unique look because of the materials and technique. I
can analyze the tone of a cyanotype and make a color photographic print that
match the tone, but it won't feel the same as a cyanotype. Similarly, I can
try my best and make a fully photo-realistic gum print, but it still looks and
feels different from a silver-bromide print. As long as there is *any*
different between alt. photo and digital photo, they will co-exist especially
when we are talking about fine arts.
And of course, archival is another issue.
Dave