I choose Cryptocurrency. People may have different preferences. Nobody gets involved. There are those who want to be rich in taking bitcoin. However, there may be people who want a more transparent economy by trading with bitcoin.
for now fiat and crypto currencies are still interconnected, and inseparable,
crypto currencies will not be useful if fiat doesn't support, but maybe the future of fiat will disappear
It depends what you re trying to accomplish. Fiat still has its very good use cases in peer2peer transfer(meaning hands to hands). But overall I'm a much bigger fan of crypto, although the technology is definitely not yet ready for global mass adoption, unless lightning really kicks in the same way as segwit did.