All other thigns being equal, I am biased toward .cc. CC has many acronyms, whereas .biz does not. On the other hand, .biz is probably more widely known amoung the general community of web surfers than .cc domains. Another thing the .biz has going for it is it cheaper renewal rate (over $10 less than .cc domains).
I have a developed .cc right now. www.vip.cc --- VIP Consumer Credit. The extension seems to fit well with this domain. If you can get a similar company name that jives with .cc, I would give .cc a try over the .biz. You always could reg both if you had a question and then forward one domain to the other.