Is hard to tell what model is the best, cuz you cant test them all! You can find 2 or 3 models in store to compare, but you can go and read reviews and some blind tests ...
UK Elektror magazine have tested 10 models [ tested by By Harry Baggen (Elektor Netherlands Editorial) ] and there is results in October issue of magazine:
The Sound of Silence - A performance test of 10 noise cancelling headphones
... After listening to a number of these special NC headphones
we can certainly conclude that most of them are effective,
albeit at a cost. Nearly all of the headphones tested here
cost £175 (€200) or more, due to the extra electronics.
However, if you travel a lot by public transport or by air
and want to enjoy your favourite music with the minimum
of disturbance, it would be worthwhile to acquire some
NC headphones.
When using these headphones the sound quality is just
as important as the level of noise suppression. What’s the
point in having an effective noise cancelling system if the
sound quality is abysmal? The comfort level plays a role
too. We’ve also made an assessment on this, but it is something
that is best judged by yourself before you buy a pair
of headphones.
The on-ear types appeared to give the best results in this
test, partially because their construction provides them with
better acoustic isolation. Usually they also sound better
than their in-ear compatriots, but it should be pointed out
that three of the four in-ear types tested here are signifi -
cantly cheaper than the others.
And the winner is... The best headphones appear to
be the Sony MDR-NC500D. This is the only one that offers
both an excellent sound quality and a very effective NC
system. As far as the noise suppression is concerned, the
Sennheiser PXC 450 was similar, but we weren’t quite as
impressed by its tonal qualities.
In the category ‘Best price/quality ratio’ the Philips
SHN7500 comes out ahead. It offers reasonable sound
quality and quite effective noise suppression, as long as
you don’t mind wearing earbuds in your ears. At a cost
of £85 (€100) Philips has placed a good product in the
market.
All of the headphones covered should be available, or
can be ordered, from audio/video stores as well as online
retailers ...
I hope this help a bit !