Well, all forms of it should be criminalised with the tacit understanding that it will still go on in the shadows.
So basically what we have now?
Criminalizing vices does not work, and prostitution is arguably the dumbest vice to criminalize. I really wish this country would stop using the criminal justice system as a tool for enforcing other peoples morals
But every single law, to a certain extent, is simply a reflection of one moral viewpoint or another. I mean, your view that prostitution should be decriminalised is in and of itself a moral judgement (I don't know how you view prostitution per se, but your statement indicates that you don't view it as being particularly morally heinous, which is of course a perfect valid viewpoint). Every law regulating everything from taxation levels to marriage and crime control to health policy ultimately stems from a moral judgement. Of course, you can argue as to whether a certain policy
is moral or not, and as to whether it is practicable, but criticising people simpy for making and supporting laws based upon their sense of morality doesn't really stack up.