My vote is for a CX bike. I have a hybrid and it's a bit heavy, and more difficult to maintain higher speeds. However, the wide tires and upright geometry are a bit more comfortable for commuting than my road bike (not to mention that I can put a rack & panniers on it and go grocery shopping).

A CX bike will be more like a road bike: lighter and a bit faster. You can get a stem that will allow you to sit up straighter if it's more comfortable.