The key is that you have to present both sides as honestly and attractively as you can. That way, it's very hard for your character to choose between them and this creates a lot of conflict, tension and emotion.
This is where many films fall down (in my opinion): they make one side obviously "good" and one side obviously "evil", so that there's no real tension about which way the hero will jump. You know they'll never pick the "evil" path so you're just waiting for the hero to figure out what the audience already knows.
