The best and the safest way to sell your bitcoins is to be a part of trusted and reputed site and it will also depend on the country that you are living in as for me localbitcoins is the best place to sell my coins.
I agree with you that there is many trusted sites for buy and sell bitcoin and you are right localbitcoins is much more better than other and i also buy and sell my bitcoin through localbitcoins and i feel safe in localbitcoins.