Usually, sitting in a LAN, I access services provided via IPv6. So I need IPv6 in LAN too, otherwise I need proxies.
good ISPs:
They provide IPv6 networks natively with global unicast addresses.
They provide IPv4 (on top) as long it is needed, using things like ds-lite or 464xlat or dualstack
bad ISPs:
You can't play https://loopsofzen.uk/
Most of them only do 🦆