I quite like the v creative and fusion-esque food on QF.
But I am hesitant to declare that they serve up the best food in OW as I've only ridden QF, CX, BA, JL and AA.
So have only tried half of OW... But the food and wines on QF are certainly my favourite in both JCL and FCL, and also v nice red wines at times in whY (at one point they had Wirra Wirra Shiraz ^). Some gems on the BA wine list from time to time, though I find BA food a hit/miss. JL is outstanding with the Japanese cuisine, though now that I can't eat shellfish I tried their Western menu in JCL which was rather mediocre. Top marks to Cathay for serving Billecart-Salmon NV in (short haul) J, but not so enamoured with the rest of the list (apart from an AKL flight where they carried one of my fave pinot noirs) - food a hit/miss and presentation could be better. A lot of the times I found the food to be overly 'seasoned', not in a nice way - they're invariably too peppery or have some kind of spicy taste. AA is quite ok in JCL and FCL, vile in whY - terrible wine list though, and only cheap Pommery or PH NV in FCL!
In whY I find CX/QF/BA all to be similar food-wise, with BA having a bit of an edge over the others. QF better with booze of course as mentioned above - ^.