You're looking for the holy grail.
For argument's sake, my money's on the horseshoe gasket between the head and the timing chain cover. I think the head has to come off for that one.
BTW, if you're too lazy to wipe the engine and look for the source of the leak, you're really lazy
What's a cam seal? The cam is completely inside the valve cover. How can a cam seal cause an external leak?