I'm going with Zurdo. He is more proven in my eye and actually tries even though he has stamina problems. Benavidez has looked good, but man I hate when a fighter has obvious talent but chooses not to use it.
Right now I'd go with Ramirez by decision. Neither lit the place up in their last fight so both men's form is bang average, in that case I have to go with the more experienced fighter. Zurdo is also a tricky customer, I can't imagine Benavidez will be able to fully showcase his talent against a high activity, 6"3 southpaw that can match him for size.
Gilberto savages the kid, mismatch unless Benavidez improves a lot. Benavidez is out gunned at this point, his use of raw size to bludgeon opponents won't work against a bloke even bigger than him. Benavidez needs to sharpen his skills and start using a bit of finesse. Gilberto is top notch tbh, just because he wins easily doesn't mean Benavidez isn't a real talent.
He's very inexperienced.. He's not ready for Zurdo, but eventually if he wants to unify he's going to have to fight Zurdo. He barely got by this last guy he fought and didn't look impressive at all.