1 Massive content sites with very good UI/UX that are similar to the free tubes but much better due to better features, format choices, content choices, etc...
Sites like
www.VideosZ.com as a good example are great for general traffic and actually retain pretty well. I'd strongly recommend revshare.
2 Small boutique sites with legal content in a very specific niche.
Sites like FacialAbuse, some specific Solo Girl sites etc have very good ratios but I'd recommend PPS
3 A lot of nonpaysites
Especially if you can find legal ways to bridge porn traffic and mainstream products/services
The EAT24 example is a very good one