Which is better and more practical, G network, C network and E network?

This is really hard to say, each family has its own advantages.

G-network: Wide signal coverage, large number of users, more mature business and more mature service. But a good network signal means more radiation.

C network: Compared with G network, the network signal is definitely not comparable, but DX is a green mobile phone with small radiation, safety and health, lower tariff and good service.