My black 6 has been described as Sinister as well. De-badging and a dark tint windshield enhanced this.
Awesome response. (although, another could post a cheetah for yellow....)
But to the OP, get whatever you know you'll be happy with if you know it's going to be a long term bike. I would've went with the yellow if the wife didn't prefer the black. That's what it took to get the 6 and I'm happy with it. All my past bikes have been black anyway.