That depends on your project needs and how much time you have available: Epoxy should only be used by those who want an adhesive product that dries quickly. At the same time, polyurethane can work well for any situation but takes longer than epoxies do. Though once mixed, epoxies cannot react negatively due to the presence of polyurethanes; this is not always true for the other adhesive product, so it may be a good idea to research your options before deciding which type you want. Keep in mind that epoxies are less likely than polyurethane to irritate and can work well with children or pets around because they're safer than their counterparts if there's any chance at all that anyone will come into contact with hazardous chemicals as you use them on your project.