I'd go for female Narcissus Flycatcher (subsp. narcissina) on this bird: supporting features being the ashy-bluish bill colour (not black as in B-W), prominent brown fringes to greater coverts (not uniform as in B-W), and thick-necked jizz + horizontal posture (more slender, erect in B-W). I haven't seen many females of either species, so I'm happy to be corrected...! ^^