The Arabic-speaking population is spread across many countries and a couple continents, from Morocco all the way to Oman. There are many spoken Arabic dialects, which are nearly as different from each other as the Romance languages are from themselves. If someone wanted to study a single Arabic spoken dialect with the purpose of communicating with Arabs across each of these countries, is one dialect more preferable than another?
My understanding is that Egyptian Arabic is the most dominant, but is it comprehensible to the other dialects, and will your knowledge of it help you understand everyone else? Or is a smaller dialect more universally intelligible among Arabs? Or are all the dialects similar/different enough that it doesn't matter, as long as you speak one of them well?
Please note that I am not referring to Modern Standard Arabic (MSA), but rather the spoken dialects that people are raised with and speak on an everyday, colloquial basis. "MSA" should not be included in your answers.