I d like the short hair version and think it suits her better, but I disagree with people just slandering the tv actress for being 'ugly'. Not everyone is designed for eye candy! After being at sea so much and fighting you wouldn't be beautiful or super skinning and muscleless either!
Love the badass pirate girl! Great position and expression.
Btw. I've only watched the TV show so far. Is she described with short hair in the books? Everyone and their mother portrays her with short hair, so I figured ... It's just that I LOVE women with short hair and it suits the character so well.