Well just stop and think. Which one do you like better? Which one do you feel more attracted to and which one do you care about more? Although some of these questions can be hard to answer, just relax and ponder on it. You don't have to come up with an answer within seconds, take your time. Let your heart sort things out first. Also think about which guy makes you feel better. I'm sure that they both make you feel good but which one makes you feel better about yourself? That's also important because you want to be with someone who brings out the best in you.
If some of these questions are tied, then make a list of their qualities. Qualities that you like and dislike about them. You can even make a vandiagram, comparing the traits they have in common and the ones that are different. These will give you a visual to which one is more appealing to you if you aren't the type to trust your gut.