We don't need to compare this two currency because they designed for their own purpose. If you ask me what will i choose for this two then there is no doubt that i will choose bitcoin because it is very profitable than us dollar and it gives me different opportunities to earn a lot of money rather than us dollar who just a fiat with less opportunities.
yes that is right that we do not need to compare bitcoin with any other currency either it is fiat or digital currency. bitcoin itself is a good currency and is becoming more and more stable as time pass. the users of bitcoin are increasing continuously and that is the reason that we can see that the price of bitcoin is also increasing. i hope that very soon bitcoin will become the main currency of the world and then people will be using bitcoin for both the online purpose as well as for offline purpose also.