Color theory is a very complex way to describe the ways we use color. In my opinion it is a bit subjective when talking about it in generality. However, when color is put into practice and used for some specific purpose it would be proper to think of color more objectively.
Munsell's work in defining color by hue, value, and saturation really connected with me and made sense when I first learned about his work. I feel comfort in defined perceptually uniform colors.
This is a fun Munsell-based hue test.