Since the term “acoustics” in this sense generally refers to how the qualities of a room and how sound is transmitted within it, the best flooring exists on a sliding scale. It all depends on what you are looking for.
To create a quiet room, your best options may be cork flooring or rubber flooring mats. They do a great job of absorbing sounds in the room. Their softness also deadens impact sounds, meaning you won’t hear as many footsteps or pin drops.
If you are recording music in the room, however, that sound absorption makes the mix feel dead. This means cork and rubber flooring for recording studios are not ideal. You need some reverberation to create a natural feel in the final product, so opt for more reflective materials. These include concrete, hardwoods, laminate, and vinyl flooring