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.
At the moment I find it both fiat as bitcoin usefull. Which makes it the discussion of which one is better futile. Just use bitcoin as how bitcoin was intended and you will see the freedom bitcoin provides every one of us, is the exact thing that we have needed all those years.