I agree with respect to UA and AA, but how does CO do better at 100K than DL in terms of Elite benefits? CO has historically had the weakest top tier program. In addition to poor upgrade delivery, they don't even give their Platinums free standby, and they charge close-in reward fees even to Platinums.

At 100K I think you'd be better off on UA or AA. But if it were DL vs. CO, I think you'd be better off with DL Plat + 25K rollover than 100K on CO.