I'm not too particular when it comes to his hair, as it really depends on the overall aesthetic. Ledger had an overall grungy appearance, and so his hair was suitably messy. The Joker's hair will reflect his general style.
What I like about the Gotham Central hairstyle is it's an unusual cut that you wouldn't see today, the way the hair forms a fin in the back. It feels very much of a bygone era.
In a previous post, I was reminded of Salvador Dali
I think I just don't want a "cool" Joker, or one that is overly stylized. I see the Joker as being a man who lives on the edges of society, someone who owns a single suit, and shoes with holes in the sole, and an old comb in his breast pocket.