Piano offers more data for making an informed, rational decision. Guitar resonates more personally for me. So, if my left brain is running this show....
The one and only acoustic instrument?
I know, I know, it’s not the real audio audition world, but if you had to critically listen to only one acoustic instrument for as long as you wanted, to make a decision to purchase a rig, what would be your lynchpin? Me: PIANO. Remember, acoustic, even for the rockers out there.