What many new hobbyists don't understand about electric motors is that the power they make is dependent on the load you put on them. It's backwards from the way internal combustion engines work. IC engine make power, then you chose a prop that is appropriate for the torque curve and power of the engine. But with electric, the prop determines the power. You can prop down and reduce your amp draw, allowing the use of smaller batteries. The only downside is you've installed a heavier motor than you needed to. Then if you need power, a prop change can increase it 20%. You can keep going until you exceed the amp rating of your motor or ESC.
So all that is to say that it really doesn't matter. The .25 equivalent motor will be at its capacity turning the right prop for that plane, while the .40 equivalent will probably have some headroom left.