I myself own the ATH-M40x's and I would totally recommend them, not to mention they come with a bag for travel. The only problem with the M40x is that it tends to get a bit uncomfortable to wear after 2-3 hours.
As Suzuki said you'll probably want noise cancelling, especially if you're flying or in busy environments. The HD 280's are good headphones but they are known to be on the heavier side which may or may not be okay with you.
Hope this Helps!