How can you even ask that? Corrales beat Castillo, Casamayor, Freitas, Manfredy, Jukko, Gainer, etc. Champion in two weight classes, Super Featherweight and Lightweight.
Valero was also a two weight champion but lacked the resume that Corrales had. His notable win is only DeMarco. You can give him names like Lozada, Mosquera, Shimada, Pitalua, add all those names and they still don't surpass a win over Castillo and Casamayor.