Does the Hadith: "Madinah expels its dross" apply to a family that moved from Madinah to Makkah, then one of its members moved to live in Makkah, and which is better: residing in Makkah or Madinah?

If leaving the city is not due to an aversion to it, then the dispraise directed at those who leave it does not apply. The hadiths that condemn leaving the city are interpreted as referring to those who leave out of a desire to abandon it or an aversion to it. Many Companions (Sahabah (definition)) left it for valid purposes such as seeking knowledge or engaging in jihad, despite their belief in its فضيلة (virtue/excellence). As for the مفاضلة (preferential status) between Makkah and Al-Madinah, scholars have differed on this matter. The majority opinion is that Makkah is superior, while the Malikis hold that Al-Madinah is superior.