The 'Eastern' refers to the Syrian dialect, which cover Syria, Lebanon, Jordan, Gaza, the West Bank and Israel. (And not as say abubasil :Morocco ,Tunisia Algeria are the western part of arabic World. Both Egyptian and Eastern are commonly understood in arabic world

Learn Egyptian dialect, the Eastern that 'are' common in Morocco ,Tunisia Algeria etc are very hard to understand to eastern Arabs themselves. Egyptian dialect is 'more widely understood in the Arabic world' due to the huge number films they produce.

Egyptian and Eastern Arabic dialects are equally understandable. I can't really recommend one over the other. You can watch and compare Egyptian and Syrian or Lebanese movies or series to make up your mind which one do you like better. Good Luck!

From conversations with arab friends from all over arab countries, the Egyptian dialect is the most common one and is easily understood in all arab countries (due to the dominant egyptian cinema in the middle east). Dialects of north-african countries are difficult to be understood in gulf area and vice versa. Stick to Egyptian dialect or Fus-ha.

It could be equally understandable lots of people , but the Egyptian one is more known everywhere than Eastern thanks to Egyptian films, songs and theater.