it depends many things... where you would like to work? what kind of job you are looking for? for example if it's about translation, so for sure MSA is the best for you, but if it's a job that needs contacting with others, and to live in the country so it is all depends on the place you would like to move to.
good job opportunities are in Dubai, Emirates, Qatar, Saudi Arabia, Abu Dabi. The dialect of these countries is Gulf dialect. and also there are good opportunities to work in lebanon, they talk lebanese. so you'll need to study lebanese dialect.
I find that all levantine dialects are so useful to learn and everyone can understand them, also Egyptian and gulf dialects are understoodable too.
It's all up to you. but if you attend to be a translator then MSA is the best for you. good luck !
Arabic, Arabic Egyptian, Arabic Modern Standard
Could anybody tell the main difference between them? For example X is similar to Y, but 30% of words are different,