You have to SELL if you want affiliate marketing to work; the set-it-and-forget-it method you use with AdSense just won't work. And it's not appropriate for many of my sites. That traffic is too untargeted to match up to specific affiliate offers. So for those sites, I'll use AdSense and direct ads.
My AdSense EPC is very high this year, almost three times what it was last year, so that works for me. YMMV.