I don't think that's a helpful framing because basically:

- For any case where BA would give you a full refund then I think that there is a good chance a charge back would be allowed to. But then what's the point of choosing the chargeback route? It could be questioned and take longer with your CC provider asking you for explanations, investigating to make sure it's allowable etc so the refund route would be a lot easier;

- For any case where you would not be entitled to a refund (for instance if you already accepted the rerouting, then almost certainly BA would successfully dispute the chargeback.

In short, I don't think that there is any case where a chargeback would be the route that makes sense, because the refund route will invariably be easier, faster, and more certain whenever it is allowable, and where it is not, chargeback won't help you.