I really think IEMs are a far better bet, but if you're decided on headphones, I second the above nomination of the ATH-ANC7. Its NR is quite good, and it's pretty good sounding overall, and it falls in the price range.
Of the passive headphones the HD280 and HD25 are the ones I would nominate for best noise attenuation, but neither one will block out Tube noise to the extent an ANR headphone will. Of the two, the HD280 isolates somewhat better but is larger (though foldable when not in use) and IMO rather uncomfortable. I find its sound dull and not particularly enjoyable, but it is fairly neutral, which for me is important with classical material. The HD25-1 is IMO a far better-sounding headphone, very clear and enjoyable, and smaller and more comfortable as well (though it does not fold up as the HD280 does). Its sound is rather bass-weighted, making pianists' left hands sound abnormally heavy, making orchestras sound overly cello-dominated, etc. But for pop and dance it's brilliant.