PONDER, why are these two the best?
Read Tafsir Ibn e Kathir of Surah Fatiha to know. (http://www.qtafsir.com/index.php?option=com_content&task=view&id=84&Itemid=35)
The Prophet (sallahu alaihi wassalam) Said:
‘The best of remembrance is La ilaha illallah (None has the right to be worshipped but Allah), and the best of supplication is Al-Hamdu Lillah (praise is to Allah).
Jabir bin Abdullah: http://sunnah.com/ibnmajah/33/145