Assuming that you meet all performance requirements and any additional company requirements like a 15% margin on runway lengths, then either runway is acceptable. That is the point of doing the numbers. As for the economics, they have to be set in context. If you need the extra minutes to get to a closing airfield or an airborne slot, then the shorter runway is obvious choice. But if you are told "de-rate" any any cost, then it's the longer runway only. But if, like most of us here, you are not given the raw numbers you will have to make up your mind. If I'm on time, I would have prepared the numbers for both but I'd flip a coin to decide.
PM