As much as I love Joker I'll never quite understand how people preference him over Ra's Al Ghul or Two-Face. I think mostly it's because Joker easily stands with these two, maybe even above them, but he's not a character that can last efficiently for many stories with his more modern, killing incarnation. Just how many stories have we had recently where Joker kills dozens of guys and Batman comes close to killing him, and then decides it wouldn't be right? I just think it reaches a ludicrous point where I can no longer take his part of the universe seriously, and turn instead to less logic-breaking characters that are still great.
Of course for things like BTAS, BTBATB, Englehart/O'Neill era Joker and such he's much, much better, since there he is written as a formidable foe without racking up kills in the quadruple digits.