I have always been a best of all worlds kind of woman, so I have (since 2006) a set of Bose Quiet Comfort 2 on ear noise cancellation phones as well as a set of in ear Shure 4c-n Isolating Earphones.
I have found the Bose set very good for both noise reduction and for sound reproduction, and as the name implies, they are very comfortable. In fact, quite often, if I wish to have a sleep, I will put them on with out connecting them (the cord can be removed).
The only negative attribute about these is that they are a little bulky, so take up some of that precious 7kg that you are allowed on board. Also, they rely on an AAA battery, so on long flights, I take a spare, and use rechargeables so they can be refreshed at the hotel or lounge before the next flight. Also, I have encountered many FAs who will ask for them to be turned off on ascent and descent. Ironically, that's when you need them most.
Enter the Shures. I have always been impressed with Shure electronics, and went for a pair of these on Amazon a few years ago when Shure were introducing new models. I got these for a much lower price than what the equivalent, then current models were selling for. I also bought an "attenuator" - a volume control, which is handy when the PA interrupts your favourite movie with news that breakfast is about to be served or turbulence is anticipated, which comes through very loud (the reason for which I can't fathom). Anyway, because they are passive (not reliant on electronics for noise cancellation), they can be used during ascent and descent.
In times of trouble, Paul McCartney found that Mother Mary comes to him. Well, for me, when there is a screaming child within the next row or so, I find that BOTH Bose and Shure at the same time make for an absolute noise cancellation environment!
As for using noise cancellation equipment during ascent and descent, I always thought that the reason for this was supposedly because electronic equipment can interfere with the plane's electronic equipment. This seems to be reasonable, however, I note that those flying F on Kingfisher Airlines (KFR) get Bose sets gratis ... I wonder if they are given out after ascent and collected on descent.
As for the "best" (although I'm not sure to what extent quality and cost are traded off), I often refer to cnet:
Best earbuds - best earphones - CNET Reviews
I hope this helps.