SeeMyGF is THE best.
I send traffic from a text link "All these pictures come from SeeMyGF" on the galleries on my ex gf site, just a text link not even a banner.
My ratio is steadily around 1:700 mark.
Tried promoting just about every single other sponsor in the GF niche, and they all do 1:1400-1:16000.
Can't go wrong with them. Plus Paul is on ICQ like 25/7 ready to help you with anything.
And not to mention 90% of the sponsors GF sites look like studio produced content, this is supposed to be a totally at home shitty camera shot niche not some fake amateur produced content.