If someone contacts me off a site...say, through email, or social media -- I direct them to whatever my current favorite site is. I prefer a site that has an 80% or more payout with chargeback protection.
If someone contacts me/finds me on a site -- I have them pay on that sites best option (whatever the highest payout option is on that given site).
I don't mention other sites on the site they found me. If they are smart enough they will find you elsewhere on there own, to speak about other preferred payments options.
I understanding that there is a bit of a learning curb for them, and having to explain to use a site can be exhausting, but I don't personally know any way around that.