I tend to buy Monsoon or Bitspower, i feel they are worth the premium - though does add an otherwise unneeded cost into your loop.
EK and XSPC offer just as good a fitting for <1/2 the price (though not used EK since they've changed their fittings)
Where i feel BP fittings really offer more than the others is in the colours and angled fittings, the colours are much better (especially the white!, so much better than Monsoon)