With that sixline present, I can't recommend much with any confidence. If you're willing to remove that fish, the door opens a lot.
So assuming the sixline disappears:
Really any Flasher (Paracheilinus) would be suitable.
Any of the more peaceful Fairys (Cirrhilabrus) would also be fine.
Beyond that, specific choices really come down to your budget and what visually appeals to you.
I would have no problem removing it. It could easily become the utility fish in my frag tank or some such thing. The hard part is....how to actually remove it.