I was doing the same research when I was building my music room. Ultimately, I decided on stranded click bamboo for the floor because of its hardness compared to other woods
http://www.lumberliquidators.com/ll/c/Xiamen-Click-Strand-Bamboo-Morning-Star-Click-PRQCBAMSTX5/10024105
I opted to go with a floating floor because with the vapor barrier and then the weight of the equipment on top of the floor, I never noticed any issues with resonances from the floor. My speakers are 285 pounds each, amps are 115 pounds each, turntable stand is 225 pounds, music rack is sand weighted and is also 175 pounds, with the equipment on both, the turntable and equipment stands, there is very little to be worried about resonance from the floor interaction, due to the mass. I did add carpet under the racks and speakers so as not to scrape the floors and to further isolate the equipment from the floor.
Ciao
audioquest4life