It depends on what kind of copper. DSL suffers from the limits of twisted pairs over medium-long distances, with only about 1100 kHz available. DOCSIS, with its shielded coaxial cable, has much higher bandwidth available, up to 750 MHz.

In practical terms, this means that DSL has already reached its practical limit with speeds around 30-50 Mbps, whereas Cable Internet still has room to grow around 2-4 Gbps, depending on how many TV channels the operator is ready to sacrifice to Internet traffic.

Of course, this doesn't address congestion / oversubscription issues around cable, but assuming a competently managed network, FTTN with coax as the last mile is still a very good choice in 2018.