Some people say bitcoin is better than US dollar but i think US dollar wins in terms of acceptance because not all people know what bitcoin is and bitcoin price is volatile and bitcoin don't have physical form you cannot touch it like dollars
For now, i think comparison should not be on which is highly accepted but on which has more value. When you want to compare them based on adoption, the US currency will always come out as a winner because it has been around for many years unlike Bitcoin which only emerged 10 years ago. Also, base on this simple comparison, I think they are equivalent though, just like every fiat to bitcoin. Each is serving their unique purpose.