Pimproll.  All time:
1:5700
And I promote at least a dozen of their sites in some form.  Next worse sponsor has a ratio of 1:1500 all time so no one else even comes close. 

 Maybe it is just me.  I'm thinking it might have to do with most of their sites that I promote being rather vanilla whereas I have more experience converting fetish traffic.
What's yours and do you have an explanation for it (other than shaving accusations unless you have proof as per the GFY rules)?