I have used both lap sealant and eternabond tape. Both work great. In my view it's six in one and a half dozen in the other. BTW, I have seen eternabond tape be not so eterna if water sits under it long enough. It is a great product nonetheless. This is assuming the you have a EDPM rubber roof. If it's something else I go with eternabond tape or some sealant that is consistent with the roof you have, ie.. fiberglass, TPO rubber, metal, etc..