Bitcoin being digital, is already a clear advantage over the paper form of conventional currencies. But since we know for a fact that there are also digital forms of dollar, yen and peso, it is meaningless to compare Bitcoin to Fiat currencies in the context of treating them both as digital. There are however key differences between the two when we describe them "not" on their digital aspect, and thus, on the following list, the focus is on these key differences, which incontestably provides Bitcoin the edge over Fiat currencies.
Without further ado... here are the list of reasons why Bitcoin is better:
1. Payment freedom
It is possible to send and receive bitcoins anywhere in the world at any time. No bank holidays. No borders. No bureaucracy. Bitcoin allows its users to be in full control of their money.
2. Choose your own fees
There is no fee to receive bitcoins, and many wallets let you control how large a fee to pay when spending. Fees are unrelated to the amount transferred, so it's possible to send 100,000 bitcoins for the same fee it costs to send 1 bitcoin.
3. Security and control
Bitcoin users are in full control of their transactions; it is impossible for merchants to force unwanted or unnoticed charges as can happen with other payment methods.
4. Transparent and neutral
All information concerning the Bitcoin money supply itself is readily available on the blockchain for anybody to verify and use in real-time. No individual or organization can control or manipulate the Bitcoin protocol because it is cryptographically secure. This allows the core of Bitcoin to be trusted for being completely neutral, transparent and predictable.
5. Bitcoin is a software
Finally, Bitcoin being a software makes it what we can term as "Programmable Money". This only means, as time goes by, Bitcoin can evolve and improve by simply updating the Bitcoin software for new features, tools and services.
Reason #5 also explains why several other coins (collectively referred to as Alt-coins) already exist in the market as these Alt-coins are all an initially-copied Bitcoin software, with modifications and trial features that explore the countless possibilities of where Bitcoin can further be improved. So reason #5 above is not entirely an advantage specific only to Bitcoin, but rather to the whole cryptocurrency industry, as we now have a tool, or what you can say a technology that can be continually modified to suit our individual needs or even the needs of the entire economy in general.
You can further your research on Bitcoin on the official website:
Most of the list of reasons above were obtained from that site's FAQ part.