all the more vs rather

all the more

adv
  • Even more; notably, but even more notably due to additional information, either preceding or following the statement. 

rather

adv
  • Introducing a qualification or clarification; more precisely. (Now usually preceded by or.) 

  • Used to introduce a contradiction; on the contrary. 

  • Somewhat, fairly. 

  • Used to specify a choice or preference; preferably, in preference to. (Now usually followed by than) 

verb
  • To prefer; to prefer to. 

How often have the words all the more and rather occurred in a corpus of books? (source: Google Ngram Viewer )