#2 is the most common way of saying which airline you've chosen, although we do also say "I'm flying/going on Cathay this time".
In #1, "with" does give some ambiguity though. If you are actually employed (as an official employee) then I would use "I've been working for ABC ..." or "I've been working at ABC ...". If you're a freelance worker, or self-employed in some other way, and ABC company are currently utilising your services, then "I've been working with ABC ..." would be fine.
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