While in this case VP9/x256 may be better indeed (they seem to preserve higher-frequency details than Daala), beware of "looks nicer" when judging codecs in genreal. Codecs are not in the business of making nicely distorted images (they're not Photoshop/Instagram). They're supposed to keep images as close to the original as possible.
For example smooth images tend to be judged as "nice", but if the original had noise then smoothness is a distortion caused by lack of detail and deblocking blur covering it up. JPEG 2000 fell into the smoothness trap: it gave it better PSNR and nice low-bitrate examples, but ultimately failed, because you don't always want everything looking like plastic.
It would be interesting to build a codec with human preferences in mind; you might end up with images that most people think looks better than the original at a fraction of the size - how you make those choices is very difficult though.
Some video encoders already incorporate perceptual optimizations (eg, x264's psy-rd and psy-trellis) that "look" better but lead to objectively worse results with traditional image quality metrics.
Audio codecs, however, have been using psychoacoustic models for decades. Frequencies outside the human hearing range are clipped, masked noises are discarded, voice codecs emphasize the range of human speech, etc.
