neither one because they are both centralized and your question is exactly similar to asking whether Paypal would become the "currency of the world"!
obviously these centralized monies have their place in the world and it won't change any time soon if ever. but they won't become dominant in the world, ever. there are always better solutions such as fiat and decentralized bitcoin.

if the comparison is only between XRP and LIBRA then obviously Libra is the winner because unlike ripple, facebook isn't a shitty small company running a shady business. although Facebook has its own shadiness but it is a gigantic company with a recognized brand.