Insomniac does some stunning stuff though just a tad too much visual overload for me. I do find "Medusa" attractive, or as attractive as one can find a freaking snake woman, and "Female Guard" is nice as well. It may be the more muted colors and the somewhat less busy environment. I tend to find many skins over saturated with too much orange/red, so I tend to be drawn to images with paler skin tones, or dark ones without the tinge. I imagine there are fundamental perceptual traits that determine preferences below the stylistic level, e.g. color, perspective, whether one likes intricate detail etc. Maybe incorporated in some 'if you liked that image, you may like these' algorithms.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken