direct IP access without port forwarding to an IP endpoint in the LAN behind your router.
I have not seen any performance of functional advantage to using IPV6 if ipv4 is available.
Many routers do not contain an ipv6 firewall, and NAT'g is not required with ipv6. These routers inadvertently create a security issue. if ipv6 is enabled and an ipv6 device is attached that does have a firewall, that device will be "on the internet" without a firewall.