* The priorities of language *users* in communication? This could be things like clarity, efficiency, persuasion, emotional expression, etc.
* The priorities of language *design*? This could be things like expressiveness, consistency, ease of learning, etc.
* The priorities of *language study*? This could be things like understanding how language works, documenting languages, preserving languages, etc.
To get a more helpful answer, could you clarify your question?
For example, you could ask:
* What are the main priorities of language users when trying to be understood?
* What are the priorities of linguists when studying a new language?
* What are the priorities of language designers when creating a new programming language?
Once you clarify your question, I can give you a more specific and helpful answer.