Bute-Zuniga was nice. Zuniga was on the ground for 14 seconds so I guess that counts as a "knockout".
Because it just doesn't look as good as any of the other ones. Hell you have to watch the replay in super slow motion about 15 times just to be sure a shot actually landed. Another good mention would be Tzyu vs Hurtado.
Rigondeaux vs. Robert Guillen about 4 days ago. Check at 5:22, slow motion at 6:30. http://www.youtube.com/watch?v=A_wI_wIDzU0
Cotto - Jennings. Sure, Jennings wasn't exactly in Cotto's level but it was a masterful display by Miguel timing his shots quite well and really testing every part of Jennings. Plus Michael isn't exactly known for going down easily.