Yes, it would be more effective to reduce meat consumption globally. But we need to do both because time is running out. See the Drawdown project for an exhaustive list of policies.

I'd argue that people who actively work on climate change mitigation should keep flying if it really helps them be more effective. One of my friends does that: she helps urban planners save millions of tons of CO2, while emitting a few tons by herself. Overall, it's a good investment.