Mid flex might be viewed as full flex. The whole rod flexes. Tip flex means the tip of the rod flexes. It depends on what you would be comfortable casting which one to choose. Some full flexes might cast like a wet noodle and that would be bad but I have a fiberglass full flex that is not like that at all. Very smooth slow cast that I like. The tip flex may cast somewhat faster than a full flex as only the tip flexes and to me a tip flex is not as smooth casting either. But some folks like tip flex because they may be a little faster casting. That is what both types of flex mean to me anyway.