Bitcoin advantages are:
Decentralized
Storing money outside banks
Sending money in a matter of seconds
Really small fees
Great currency for online payments
Blockchain that can be used for various purposes
Fiat advantages are:
Acceptance everywhere in the world.
Best payment tool in the offline market
Offline payments are an advantage that fiat has over Bitcoin that is the only feature Bitcoin can't mess with or overtake. That being said, cash money is being used less and less as people use their smartphone and bank card with NFC to pay for things. This is a market where Bitcoin can land in and start being something of importance.