What is the most popular wood finish ?

Another vote for rosewood, looks great to me and has a high WAF. I do also like other "darker" wood colors. The Makore finish on my Verity Audio speakers was absolutely stunning.

I've always been a sucker for maple. There are so many variations that it would make it hard for me to choose.
All the best,
Nonoise

Rosewood and other exotics will not necessarily be good for resale. As you say, keep it neutral. Maple or cherry are good choices. And you are correct, rosewood, ebony, and others will run you 500 or more just for material. Depending on how good the craftsmen is, the labor cost will be high. I've veneered many speakers in my day, to be done correctly is not an easy chore. Raw veneer will give a much better finished product than backed material, but is a lot more labor intensive.

I would think cherry or walnut would be safe choices. A lot of the exotics can be too taste specific. Just use a natural stain and a clear coat. Make sure you see samples by whoever is doing the work for you.

Natural Cherry.