As far as these 2 titles are concerned, Def Leppard wins. They are more liked by the female audience (hence easier to get the family pin buyer) and the group is still touring actively. Also since they are from the British heavy metal movement they would transcend better globally in sales.
However I'd love a classic Roth era Van Halen pin myself.
*Didn't Nikki Sixx say on his Sixx AM radio show a Crue pin was coming ? What happened with that ?