Donaire v Showtime 4

Which of the Showtime 4 would Donaire have the most problems with? We've seen what he can do to Darchinyan once - Would he do it again? Mares is pretty slick but could his chin hold up to Donaire's best shots? It's just my opinion but I can't see Donaire knocking either Perez or Agbeko out. They both seem solid around the chin area. They're both pretty relentless with their come forward styles. I'd love to see how Donaire would handle either of them. Donaire against either of these 4 would be worth watching. I'm just interested to see what everyone else thinks. Who would be Donaire's toughest fight of these 4?