Equilibrium climate sensitivity - ECS - is easily-understood as the global mean atmospheric warming for a doubling of CO2. It is widely applied, has been studied for over 150 years and is therefore appealing as a metric for communication of climate model results. However, here we argue that ECS is not a good metric for comparing different climate models and is no longer appropriate because of expanding model design and conditions. Using brief examples concerning the Pliocene epoch and the Paleocene–Eocene Thermal Maximum, it is further posited that models which produce temperatures towards the higher end of model intercomparisons are useful in spite of recent studies concluding that these models are `too hot'. It is hoped that this brief manuscript generates discussion on how to prioritise the consideration of more useful, and potentially novel, ways of comparing climate models going forward.