I'm from Tunisia, and I can rank the Arabic dialects according to its presence on tv (programms, tv shows...) : 

- Egyptian

- Levantine (Lebanin,Palestine...)

- And then come the others

I hope I gave you an idea about the Arabic dialects, until other Arab answer you.

Assalamu Alajkum ( Peace Be Upon You )

in Arabic language , you have to know that there the formal and informal .

- Formal or ( Al fus-Ha ) as we call it in Arabic , it is the official one and it used in media ( News TV , Newspapers ... ) at school , at work , Books , and all Arab countries can understand it well .

- informal or ( Al 3amiya ) it used by the ppls and every Arab countries has a different dialects , like ( Egyptian Arabic , Morocco's Arabic , Gulf Arabic .... )

the Arabic dialects it's different and there are groups like

( Lebanon, Syria, Jordan, Palestine ) shaamy dialect

( Morocco, Tunisia, Libya, Algeria ) Moroco dialect

( Saudi Arabia, Kuwait, Bahrain, Qatar, Emirates ) Khaliji dialet

and Egyptian dialect in unique

All dialicts using Arabic words but in different tune or sound ( not All words )

you see every group of these dialect have it own sound system, regarding in there backgrounds and you can recognize it when you here it.

i cant's say what is the best dialict because every one will say his dialect or accent are the best but  this depend on you. what dialict you wont to learn and why?

Good luck.

Julia, Egyptian and Levantine dialects aren't similar, so it will be hard to understand Levantine if you learn Egyptian, and vice versa. But I always suggest to start with MSA, so you won't find dialects hard to learn.

Thank you! But if I will learn Egyptian dialect, will it be easy for me to understand people from Lebanon for example?

<em>hi</em>

<em>you can learn the classic Arabic"اللغة العربية الفصحى" </em>

<em>it will help you to deal with any kind of Arbic dialects </em>

<em>becouse the differant between any kind of dialects and the classic one  isn't big </em>

<em>and if u speak classic arabic "اللغة العربية الفصحى" any one  speak arabic will understand you </em>

<em>in any country in arab regin .</em>

<em>hope  that my answer help you !</em>