禁漫天堂

This is just a hunch really, but I would say dentist. There is a lot of competition for flight attendant jobs because of all the travel and other perks along with the rather minimal entry requirements to get into it, and, well, Americans are too lazy to learn a lick of a foreign language and there are limited non- English speakers coming into the country and requiring ESL right now. In short, I don't think the chances of getting a work visa to be a flight attendant or ESL teacher would be that good.
At least there's a demand for dentists or possibly other health occupations like respiratory therapist or physical therapy assistant, sonographer, etc. But good luck with any of these while the totally anti-immigrant president is in charge. Some of us are trying to get out of here, in fact.

Medical professions require US license/certification.

Considering OP's range of career wishes research into professional future is in the early stages. Maybe an exchange year or aupair might be a good start.