I'm curious why you want to marry one over the other when you love them both equally? Of course, everyone sees marriage differently, but in my case it was a way of saying "I might love other people, but you'll always be my #1"
Beyond that, I don't see any reason to make plans right now for "some day" ... you're young, you have the rest of your life for "some day" to come. In the meantime, it's important to enjoy life. Your heart, and your boyfriends' hearts, will tell you all what to do when the time is right.
I don't need labels to define me. They're sticky and I hate the glue they leave behind.