A: If you’re looking purely at durability, then an oil-based polyurethane is still superior, but only marginally. There used to be distinct differences between water- and oil-based polyurethanes when it came to durability. Today, the differences are fairly minor.
Oil-based poly will be slightly more resistant to scratches, moisture and heat when compared with water-based poly.
So, why use water-based when oil-based offers improved protection? There are three primary considerations: color, odor and drying time. Some woodworkers dislike the yellow cast oil-based polyurethane puts on white woods, such as maple. In general, a water-based polyurethane will not add color to the wood and will preserve the wood’s natural tone. On woods such as cherry or walnut, this can be a disadvantage, because a straight water-based finish can make the wood look cold and uninviting. That’s why finishers often use a seal coat of dewaxed shellac to impart color and warmth before they put on a water-based finish. Another consideration is odor. Water-based polyurethane will give off little if any odor compared to oil-based poly—a real issue if your finish room happens to be in your basement. Finally, water-based poly dries a lot faster, giving dust less time to settle out of the air into your finish.