your body "feels" partial pressures of inert gases. If all other dive parameters are the same, especially time, then when you use nitrox you are exposing your body to less inert gas so you should feel a bit better. How much will depend on how rich the mix is. If however you are diving to NDL on both air and say EAN32, then the total inert gas load is essentially the same and you should feel no different.
From the DAN Article...
"Given an identical dive, it is generally understood that the higher partial pressure of oxygen in nitrox — and the lower partial pressure of inert gases — will result in less decompression stress. It’s easy to make the logical leap to connect fatigue to minor decompression stress at this point, but it’s important to recognize that a higher partial pressure of oxygen also causes a different type of stress: oxidative stress. Several studies suggest the oxidative stress generated by high partial pressures of oxygen can cause mild endothelial dysfunction, which might actually lead to feelings of fatigue."