I choose by flavor, because a strong mint makes me gag in the morning. But I still enjoy mint flavor! So I usually have 2 tubes out: one mint flavor to use at night (right now it's Aquafresh iso-active whitening Deep Impact---in the can, but I also use Tom's of Maine peppermint (with or without fluoride) sometimes. And I think I'll try Sensodyne next because I'm having some sensitivity issues) and one non-mint flavor to use in the morning (right now it's Crest Complete citrus splash, but I also use Tom's of Maine childrens' strawberry flavor, or their apricot "homeopathic" formula). It's not easy to find non-mint toothpaste!