Better "Noise Cancelling" Headphones for Air Travel?

Full disclosure, I know next to nothing about headphones. I own a few pairs of ear buds and a pair of Bose noise-cancelling headphones for air travel and cutting the lawn. However, I have an upcoming international trip with my wife that seems a great excuse/opportunity to upgrade to a decent set of headphones. My wife won't care if she get the new set or the old, we can't both use the one pair, and it's a long flight.

For the trip, I'll be pairing my headphones with an iPhone/iPad & Dragonfly Red DAC that I already own. Budget is flexible but I'd don't want to go crazy...I'll probably spend <$500 but don't mind if people discuss other options within shouting distance of that amount to generate conversation.

My questions are:
1) How well do passive noise cancelling audiophile quality headphones cancel out the constant drone of a jet engine?..specific recommendations for those that would do it well, if any, appreciated

2) With that much background noise, are higher quality headphones even worth it or would I only notice the benefit in a quiet environment?..I'll probably stick to sharing my music with the family when in my own home so these aren't going to get tons of use outside of traveling.

3) Any recommendations for a pair of active noise cancelling headphones that sound better than Bose (QC35s) with the active noise-cancelling feature engaged?

Thanks in advance!