If we're talking about these guys in relation to pick #10, for me I wouldn't consider Horn there, but he would be one of my targets if we traded down into the teens or twenties.
Now, to me, the choice between the other two at 10, depends on what we do in free agency.
If we sign a FA who is at least a capable starter, I'm taking Farley over Surtain as I feel his ceiling as a play-maker is higher, but he will need some time before he is ready to be an everyday starter in the NFL.
If we don't sign a good stating caliber CB in FA, then I'm taking Surtain as I feel he has the higher floor, is more technically sound and is more ready to be a day 1 starter.