My wife and I have seen both the carbon and sapphire black and we both chose the sapphire. The carbon is just too blue in my opinion. Plus, I've had dark blue/black cars before and I've always wished they were more black since most of the times they look blue. They really only look great when they start looking more black.
Don't be fooled by most of the pictures on here that show carbon black as well. The pictures always show them looking more black than anything else but in real life it looks more blue for sure than black ...only in low light will it start looking black.
I would definitely say see it in person before making a decision. Seeing it in person made the choice for us. Maybe if we never had a blue/black car before we could consider carbon black more