The correct answer to this open question is the following.
Although there is no specific context or further reference, we can comment on the following general terms.
The most important things you wish you knew about your customers are the way your customers think to know what they expect of you and your products. This is really important for you because today, customers have many options to decide what to buy and where to buy. So you have a lot of competitors.
So the more information you have about your customer's behavior, the better marketing decisions you are going to make.
Yes, there are current data points that might reveal this insight for you. Almost all digital marketing agencies offer different services based on marketing analytics so you can get a pretty close idea about the segmentation of your consumers. Indeed, there also many marketing apps that can help you with your marketing decisions.