Well, pick one. If you pick the wrong one, don't marry him.
...seriously, I would go with the one you like more, and let him know you like him by either asking him to go out somewhere or outright or by paying more attention to him or something. Because if you go with the one you don't like as much... just think of
your boyfriend really wishing he could be with someone else.
Speaking of marriage... don't get engaged in high school. Just don't. >>