Best friend romance. How do I catch him by surprise and be more obvious about my feelings for him?

Honey, he said that he "isnt sure" who he likes, because he wants to leave his options open. That means he will take anything that you offer him, in the right now: Time, attention, handholding, you name it, whatever, etc. until the girl that he is truly interested in comes along, then he will drop you as his "best friend" and pursue her. This is what men do. They are wired that way. Good luck.