Is it better to use pure-Korean words or Sino-Korean words?
Or does it change for every word?

For example,
바닷가 and 해변
제일 and 가장

Question

Is it better to use pure-Korean words or Sino-Korean words?
Or does it change for every word?

For example,
바닷가 and 해변 
제일 and 가장

Answer

it depends on the situation and the context, usually to sound more academic you use the sino korean words but always make sure you use matching ones. aka don't use pure korean and then switch in the same sentence.