Although Modern Standard Arabic is the formal language of all Arab countries, Arabs don't interact with each other on a daily basis in the formal language. Each Arab country has its own dialect; Egyptian Colloquial Arabic is the language through which Egyptian people interact. Egyptian dialect is the most widely spread and commonly understood among Arab dialects due to the enormous popularity of Egyptian Art and Media. Also, one can see the written forms of ECA in Egyptian social media, street signs, some Arabic modern literature, etc. Learners who choose to study Egyptian Colloquial Arabic target mainly the oral form of the Arabic language (speaking-Listening).
Modern Standard Arabic (MSA) is the modernized version of classical Arabic which is the language of the Noble Qur'an and all Arab religious texts.MSA is exactly the same across the Arab world as it is the official language of all Arab countries. There are no local varieties of Modern Standard Arabic and it is taught at Arab schools, colleges, and universities. It appears in written forms including in literature, books, media, newspapers, magazines, official documents and correspondence, etc. It is also heard in spoken formal forms including TV news and debates, speeches, government and parliament, conferences, seminars, summits, religious sermons and assemblies. Hence, if the student is targeting the written and official form of the Arabic language, Modern Standard Language is the best choice.