Who I want dead and how:
Matsumoto and Gin, dying in each other's arms after a fight to the death, both die before saying "I love you." Leaving their emotions eternal unrequited.
The anemic dude and his pink coated buddy, they go down in a back to back blaze of glory against a million Espada and Aranncar that were pulled from Tite's ass.
Soi Fong, double K.O. assassinating Aizen. (That's right, Ichigo WOULDN'T be the one to kill him.)
The Furry, dies in fire.
Byakuya and Rukia, I don't care how, they just both need to die.
Kenpachi, in a singular awesome blaze of glory, cue the sad scene of "He can't work if they bury him in the ground." (Okay, I somehow doubt Yachiru's that innocent.)
First squad captain.
Hitsugaya, dies because Hinamori thinks there's still good in Aizen, is proven horribly wrong and Hinamori is forever cursed with the guilt of having killed Hitsugaya.
Finally, Orihimei, realizing all this is because of her, she erases her own existence.