Channeling summons a lightning bolt when a mob is hit by a thrown trident if there is currently a thunderstorm occurring. The mob must be exposed to the open sky for the enchantment to work.

Is channeling good Minecraft?

It is completely up to you. The only benefit of getting channelling on a trident is to collect mob heads by making charged creepers or turning villagers into witches or turning pigs into zombie pigmen.

Is channeling or Riptide better?

Riptide launches the user in the direction the trident is thrown, making it a perfect weapon for close up melee fights. Channeling is on the other end of the spectrum, summoning lighting if it strikes a mob, making it a brilliant enchantment for long range fighters.