Which is more entitled to lead the prayer: the lisping person who cannot pronounce the letter "rā’" properly, or the non-lisping person who cannot recite the Qur’an with the correct rules of recitation?

The lisping person can only lead others who also lisp in prayer. The leadership of someone who does not master the rules of Tajwid (Qur'anic recitation) is valid, as long as they do not substitute a letter in Al-Fatihah or make an error that changes the meaning.