What language was Jesus most at home with?
That is a tough question.
Well the language Jesus would have been most at home with was the language he grew up with during his formative years. Now according to the gospels Jesus, Mary and Joseph fled for Egypt when he was an infant. How long did they stay there? In the Gospel of the Infancy it is stated three years; in the History of Joseph one year; in Tatian's Harmony seven years ; by Epiphanius two years. Athanasius makes Jesus four years old when He came from Egypt; Baronius eight years.
The average time of all of the above is 4.1 years.
At approximately 2 years of age, a child's ability to use language suddenly increases rapidly. The size of the vocabulary increases and they begin to string words together in short sentences. The ability to represent objects, people and events through language, develops at about the same time as representation in children's imitation, play and other actions. While representation is not required in uttering simple individual words, it is necessary for organizing words into simple statements.
So I would have to say Egyptian... definitely Egyptian.