I don't seem to mind two tone colors either. The best smudge resistant color to me is generally matte GRAY and SILVER just because black in plastic, glass, or matte attracts smudges the easiest.
Asus Zenfone 5 with red or gold rear looks pretty good to me. Same with the Oppo Find 7a with a white rear although I prefer the sandstone black of its OnePlus cousin. I can dig cyan or magenta like in the Nokia Lumia 800. I can dig purple like in the HTC Windows Phone 8X or red like in the WP 8S. I guess it all depends. Sometimes I like two tones, sometimes I like all-white better on certain devices like Samsung Galaxy devices, and sometimes I prefer black front panels like on every iPhones except 5s and every Sony Xperia.
For iPhone 6/6 Plus, I don't find it attractive but I find the black option the best of the three. It doesn't mean white is feminine as Apple made a living during the pre-iPhone era making white the standard color for Macs and iPods. Does owning white iMacs or iPod classics (pre-6th gen) with white headphones make guys feel feminine? White was the new black for Apple during the early 2000's. I started liking white on electronic gadgets since the off-white SEGA Dreamcast even before Apple started standardizing white on their products a decade ago or Nintendo tried emulating Apple with their white DS lite and Wii as the default color option in 2006.
