The business that has the least number of existence in your location could also be a possible business idea that can be profitable to anyone who is willing to establish it.Try to see what problems people are facing in your area or try to find out what product the people in your area will find useful and interesting. This will help you get a product idea for your next business.
But in general I prefer any business that deals with selling or maybe manufacturers of edible products as they are always on demands.