Oh and my friends says, 'They're all good, except the fifth one, the fifth one sucks.' Don't take him seriously though, he doesn't really know what he's talking about. But at least he likes the first four.
But on a more educated note, the pose in four is rather unflattering in my opinion and the second one is an odd angle and her chest is rather blotchy which is certainly not flattering. It's hard to critique portraits on a model-basis because I don't want to piss people off.