Which language would be more useful to learn?

ASL, because you will meet more hearing-impaired people than Arabic speakers. Presumably when you refer to a career in translation/interpretation, you are not intending to translate/interpret either of these two. Anyone who starts a new language in junior college will have a very difficult time reaching professional fluency within a reasonable amount of time.

In addition to improving your nonverbal communication skills, the study of ASL raises many important scientific questions about the true universals of language and language variation, as well as their developmental and neurological origins.

And here's another reason. When you become a parent, you will be able to communicate better with your preverbal children.

It actually depends on where you live. usually larger cities have group of Arabic speaking people. So if you live in a large city Arabic might be good. The deaf can be found everywhere but aren't usually localized in any one area. ASL is a lot easier to learn that Arabic so that might be incentive. I wish you well in your endeavor. I know ASL myself but could never earn a living doing it where I live.

Depends entirely on what you might want to do. Certainly Arabic is in huge demand considering some 1/2 billion people speak it......

Spanish alot of people in Ca are from Mexico

depends on what you plan to do

if you join the military, they actually need more people that can speak arabic languages