Operating Cost or Running Cost (ie fuel and lubes are one thing, but the wage of the cook in the airmans mess in Lyneham and the cost of simulator etc are factored for Operating cost - or whatever they are called)...You will get a moderate number for one and a Huge cost for the other.
If you were to charter them out, as a company you would use the latter, as you would expect to pay for the airframe etc by the end of their use..