Red!
Its dark brown naturally so it doesnt dye well, and its already frizzy so bleaching it makes it even more frizzy. So red is the best I can do that will actually show up and not clash horribly with new growth.
You got yours dyed now huh?
I need to dye mine again its somewhat faded
I still get compliments on it occasionally though so I know its at least a bit noticeable though!