Are there differences in quality among different sealcoats?

Yes, but again they tend to be minor. The most commonly used producers in the SF Bay Area are Overkote (Reed & Graham), Graniteseal (Graniterock), Tri-American, and Western Colloid. As with many other products, there are pros and cons of each with variations in longevity, depth of color, effectiveness on new versus aged pavements, etc but they are similar enough in both appearance and cost that most customers are unlikely to notice a difference, particularly if surfaces are sealed regularly at 5-7 year intervals. On rougher surfaces, the addition of sand and latex additives can improve the longevity and performance of the sealcoat and replace fine aggregates lost to erosion/raveling. If conditions dictate, we may recommend one material over another or encourage the inclusion of additives.