I've owned a black iPhone 4, slate iPhone 5, gold iPhone 5s, and temporarily used a white iPhone 5 before giving it away to my cousin because the battery life became crap. I also owned a white iPod 5th gen and white Nintendo DS lite where the latter's matte shoulder buttons got dirty easily.
Since I am a guy and tried all different colors on phones including a navy blue Sanyo SCP-5500, glacial silver HTC One M7, dark gray Nexus One, and gold LG G3 Beat. I prefer black front panels on an iPhone. So space gray. Just go ask Sarah Palin when her hubby isn't around, once you go black...
Rose gold and champagne gold are horrible color options for guys but get what you like. Apple is still years behind Nokia's customizable backs from the early 2000's and Moto Maker from 2013.
Space gray or silver are the only choices for me. Apple should give us more iPhone color options beyond the hideous colors of the 5c and more like the 4th gen iPod nano..
Nine color options
^ One of the rare times a gadget in orange looked really cool to me.
4: White (yeah, I waited for it)
6S: Space grey (because the white bands look ugly on the other colors. Would've gotten gold)
I really wish for a nano chromatic iPhone. The color combinations on iProducts are kinda boring nowadays, especially since every Android OEMs now copied the same color scheme. Metallic green, or blue would be sweet, but I can see Tim Cook as a boring man that prefer streamlined and simplified supply chain.
I have had most available colour combos since my very first iPhone.. see below:
iPhone 5 - White / Silver
iPhone 5s - White / Champagne Gold
iPhone 6 - Black / Space Grey
iPhone 6s Plus - Black / Space Grey
iPhone 6s - White / Rose Gold
iPhone 7? - Will get the newest colour option if not back to White/Silver to start cycle again!