Wizards have more skills.
Sorcerers are better in social skills.
Sorcerers can be better specialists. Be it blasters, or my preference, enchanters are much better as sorcerers. The bloodline powers give them bonuses that the wizard doesn't get and those specialists need high DCs or they will feel useless.
Have an idea of what you want to do with it, and if its a specialist, then look at bloodlines. If their is a bloodline that gives a bonus to it, then its a good choice. If there isn't anything, then a wizard might be optimally the better choice.