What is the difference among beneficial, advantageous, and favorable? And in the following sentence, which one is best?
we will seize the favorable opportunity of world peace and development, to develop ourselves while at the same time promoting world peace and development with growth.
Without doubt you should add a superlative form to your adjective and in this specific case the most effective adjective to use is advantageous. So your phrase will be like:
We will seize the most advantageous opportunity ...