Which do you prefer? The one who's all serious, and evil-for-the-sake-of-evil, or the more glib and urbane interpretation who dates people on dates, chills with bartenders, and just tortures mortals because he's bored and it passes the time?

I personally find it more interesting to see him behave more human. It's more effective for a villain. Because he can almost charm you into thinking he's just a wisecracking rogue, until it's too late and you realise you've been conned out of your own soul.