I feel like people are going to just vote for whichever one looks "coolest" and thus pick number 6. But I don't think it best represents DRK and is somewhat shortchanging the project. Darkcoin has a lot of innovation going on in all areas of cryptocurrency, not just privacy. DRK is clever and sophisticated. Thus, the logo needs to be clever and sophisticated. Some of the other choices much better exemplify this, but won't win. Maybe that's okay though, as the logo's purpose is more just to be appealing to the average person than fully embodying what the coin is.
I actually think the logo's purpose is somewhat deeper. One aspect that I believe is crucial to Darkcoin's survival (once source is released) is remaining competitive against a carefully branded clone that intentionally avoids any of the "Dark" baggage. If we were to go open source right now I believe we'd be wide open to being completely dominated by a "light"-branded clone with strong marketing. Look at how well Hirocoin did in mere weeks, and it doesn't even have Darksend. Selecting an accessible, mainstream logo that avoids any dark connotations and doing some major work on branding reduces the scope for this.
I completely agree. But, as I said above, I think the purpose will get lost in the masses voting just based on what looks cool.