it depends what you mean by best.
I have a david clark, cost me in the region of £200, I find it's been reliable for the last 3 years, is comfy to wear for long periods, and has pretty good sound quality.
Are there cheaper on the market that would perform just as well? probably, yes.
Are there better headsets available? Yes, a lot of people complain the david clarks grip your head too tight. I've never suffered this problem, but i've known people sell their headsets at a loss because they didnt like them. the bose-x is aruguably the best on the market, but costs about 4 times as much as a DC.
My advice would have to be to try before you buy if possible. If you can try on several headsets, and if possible take a couple flying, then you will know what's best for you.