I dislike cake mixes.  I will be the first to admit that they can be real time savers, and I have been known to use them when I am making a wedding cake or such as that…but for the most part I dislike ingesting things that I cannot pronounce, and as a linguist, I can pronounce nearly anything.
Making your own cake mix is the answer.  It is fresh, you know what is in it, and it stores well for up to three months.