A search of this website on the topic of soundboard wood will expose you to every opinion you could want to consider. And some facts as well. enter
the words "cedar" , "spruce" "soundboard" in various combos. A "vs" or a "versus" will produce more results.
Koa or Mahogany would be eccentric. That's my eccentric opinion.
Cedar when new sounds like it will sound in 20 years. Spruce tone develops over time. Spruce tone is different from Cedar tone. New Spruce tone is
still Spruce Tone. This is consensus opinion.