When would you choose a global unicast IPv6 subnet instead of a unique local (ULA) subnet?

Choose a global unicast IPv6 subnet when the subnet must be routable over the internet. Global unicast addresses are publicly routable and globally unique, similar to public IPv4 addresses. Unique Local Addresses (ULAs) are designed for private use within an organization and are not routable on the global internet. Therefore, ULAs are chosen when the subnet must be available only within an organization, does not need to be routable externally, and serves a similar purpose to private IPv4 addresses (RFC 1918).