As the designer of #8, I still think #6 is by far the best. #2 just seems a bit too busy and probably won't scale well, but it seems like some people like it more than #6 because of its color scheme. The color scheme can be changed very easily, so I think we should bet too hung up on a design because it's "darkness" or lack therof. I think that's something that can be settled after a design is chosen.

Just an example of what could be done for those who think #6 is too dark (using #2's color scheme):