better vs top it off

better

verb
  • To become better; to improve. 

  • To surpass in excellence; to exceed; to excel. 

  • To give advantage to; to support; to advance the interest of. 

  • Had better. 

  • To improve. 

noun
  • An entity, usually animate, deemed superior to another; one who has a claim to precedence; a superior. 

adv
  • Greater or lesser (whichever is seen as more advantageous), in reference to value, distance, time, etc. 

  • Had better. 

adj
  • Greater in amount or quantity 

top it off

verb
  • To emphasize or underscore; to make something even better or worse. 

How often have the words better and top it off occurred in a corpus of books? (source: Google Ngram Viewer )