make a pro/contra list (answer from TheOneFromMars)
If you're truly stumped, a coin toss should do the trick.
surely there's one that's better than the other. if they are equal in your eyes. i would go for the one who is nicest to you. if that's equal, i would pick the less pretty one because she must have other good traits which will last longer to balance out her lack of relative beauty if you consider them equal. - hopefully that last part made sense. and if they really are the same, it doesn't really matter, but picking the less popular one will usually give you less of a chance of being cheated on. if you still can't decide, get out the coin.