Another factor is how good the mike is.
The mike has to deliver good speech reproduction (many quite obviously don't) but also has to have good noise cancelling behaviour.
All aviation headsets have NC mikes but some are better than others. Any un-cancelled noise at the mike will be heard in the headset - not what you are paying for!!
Recently, I upgraded a couple of my 4 Bose ~ 1999-2002 headsets to the current mike (which incidentally has about 2.5x higher output, measured on a linear millivolt scale) and on the next flight was concerned that the engine wasn't making full power. The indications (fuel flow, IAS, etc) were spot on, and eventually I realised it was wholly due to the new mikes having much better noice cancellation. Yet, the old headsets were still miles better than anything else out there.
Further evidence for how good the Bose is now comes from making the occassional movie, when a miniature mike is tucked inside the earcup. (For best results, the camcorder needs to have a manual audio recording level control). Now, the recordings are almost silent, except for the intended speech.
Bose had a big "incident" a few years back when they shipped out a huge number of duff mikes. They fixed the headsets under a specially extended warranty but (gosh what a suprise) this was severely under-publicised in Europe and also they washed their hands of it a lot faster over here. Even with the duff mikes the headsets were better than the other brands, but it does show up with some intercoms. I am puzzled about the full extent of this mike business because I recently had all four of my headsets tested by a Bose dealer and all four were the same, 2.5x too low on mike output, and they were made over a 2-3 year period..... It's possible this was a well covered up manufacturing error which actually went on for a long time. I would not buy a used Bose unless it has the new mike, otherwise it's another £130+VAT.
Bose are way overpriced for the content of the product but I suppose if one takes a long term view of one's flying life.... I would not recommend a 1 hour PPL student getting one.