To compare the two is hard really, AFF is for a much wider range of traffic and will convert very well on a wide spectrum.
If you have a variety of traffic - AFF is better
Streamray is more specialised and therefore will not convert as well with a wide range of traffic, but with some cams traffic ( SE especially) cumtv, cams.com, camgirlslive.. will convert and retain and bring you long term revenue with the 20% revshare
If you have cams traffic - Streamray is the shit
Personally, I have just captured some AFF SE traffic and its converting at about 1:100 with an average of 55% of 50$ ( average signup and % revshare ) Tomorrow I will start working on a keyword that is about 1300% more volume
I just finished an SEO page for cumtv.com and expect it to be indexed in 3 days or so, if it looks promising, I will add a couple more higher volume keywords to work on to my schedule
both rock !
www.aff.com www.streamray.com