I think it depends on the effect you want. If you want a bright cheerful one, then the first red. If you are going for that calming and relaxed the blue.
Falling Charms is a great pattern for using completely unrelated or scrap squares. I would use them all!
I'm with Tartan!! I'd find a way to use all of them with one being dominant and the other more of an accent. So it's a blue quilt with red touches or vice versa.
