If you're willing to pay for the link, I'm assuming your site/landing page has some goal (like sell products or email signups).
From what I know about porn traffic, it's not so much the volume of traffic, but the quality. So assuming both sites have the same domain metrics (not always a reliable factor), choose the site that will achieve your goal.
The only accurate way you'll know this is by tracking data (like G Analytics or a tracking system) and see which site has the best quality traffic that converts for your site.
