I've killed a lot of sims for the Black Widow Challenge and I've gotta say my favorite way to kill sims is either drowning or hysteria. I've tried starving but it takes soooo long omg. But what meth...
Death by MCCC is what I use...it's immediate. I think I like the electrocution best. I used drowning once, no more, puddles everywhere when the ghost comes out. :p