Modern Standard Arabic (MSA) is a good foundation. Darija (Moroccan Arabic) is probably furthest away because it is heavily influenced by the Berber languages

Modern Standard Arabic (MSA) is a good foundation. Darija (Moroccan Arabic) is probably furthest away because it is heavily influenced by the Berber languages (and Arabs are not the majority in Morocco, they are just the largest minority). Also, Moroccans tend to do lots of context switching to French. Egyptian Arabic is widely understood everywhere due to Egypt's strong position in the Arabic movie/TV industry.