Shigurui Death Frenzy easily, You see a guys brain fall out the side of his head for Christ sake! and i've seen all that have been mentioned. I find there's two types of gore though, Gore you know that's going to happen and the gore that is shocking; like when one of your favorite characters gets killed unexpectedly in a 'gory' way. Blood-C demonstrates this well and it is very disturbing. Nene Motoe's death is very unexpected
Blood-C spoiler -^