Donaire. Donaire's left hook decimated hardcore Mexican dudes. Garcia's left hook wrecked a glass-chinned Pakistan and a 50 year old Morales.
I was going to say smokin' joe. (edit, my bad, I always forget tommy morrison, amazing left hook) But then I only had two options XD Nonito, I like his left hook better. I have always thought that garcia's left hook lacked of all the precision and timing that a top notch left hook should have, maybe because of the amir khan fight. He missed so many left hooks because of precision and timing, and it's clear that I havent forgiven him