We used to make some packet cake mixes, but found most has a base flavour across all cake types and didn't find them special....they tasted like packet cakes. The standard flavour used in packet mixes from memory has slight vanilla undertones. They also are sweeter than we would prefer.
We now make all our cakes from scratch, including banana bread. The secret to a good banana bread is using overripe bananas....the ones which look a lost cause and mushy inside. These bananas are sweet and have a more intense flavour. These bananas also allow amount of added sugar to be reduced to near nothing, without compromising taste.
We also found packets convenience no different to making our own....as there is the same amount of clean up. ..and measuring out base ingredients possibly takes a few minutes more.
We plan to stick to cakes from scratch in the future. Baking from scratch is also good for getting children's involvement, and increase their understanding of what goes into different foods.