what kind of phone? not all support the better quality Bluetooth codecs, aptx on the android side and aac on the iPhone side.
if your phone and BT receiver don't each support a high quality codec, routing the headphone Jack on the phone to an input on your receiver will be the better choice.
the fallback lowest common denominator audio codec for Bluetooth is really that bad.
if you can get BT running over a high quality codec, it will be competitive with most headphone jack outputs but not, IME, better. if wireless is important, of course it's an easier approach than running dlna over WiFi, but a network connected player can sound excellent, better than the BT codecs can.
I say this having two apt-x capable receivers in the house. fortunately, neither requires BT as it's sole input, and I wound up using one solely via its analog input (a grace digital tpa 3116 integrated amp played though speakers) and the other solely as a wired DAC and headphone amp (arcam irdac ii, played either through a receiver or directly to headphones.)