I really like the Valentine Hybrid.
Here is a link to some interesting info.
Basically if the pigment is from lycopene, consistent high temperatures are necessary for good color, like the star ruby grapefruit from the Gulf Coast, as well as Cara Cara oranges.
If the pigment is from anthocyanins, then the best color is achieved in a climate with significant day/night temperature variation.
Usually this happens where it is dryest at lower altitudes. Inland desert valleys on a cold current (West) coast are perfect.