Before you even begin to speculate about what the best business opportunity is, lets make this simple. The absolute best business opportunity for you is the one that interests you and inspires you to do great work. This is exactly what many people lack in their day to day jobs, so it doesnt make sense for you to find a business opportunity that puts you in that same position. Instead, choose something that you are genuinely passionate about, and that passion will often be enough to make you successful.
Its true that you can do all kinds of research about which markets are pulling in the most money, and what the top franchises are at any particular time, but unless you find something that you want to do, it will be just like any other job. There is nothing inspiring about that, and it certainly doesnt make you want to run out and start or buy a business right now, does it?
When you are trying to decide what the best business opportunity is for you, think about all of the resources that you have available, and what you think your community needs. If there is a particular store that you go by every single time you have the chance, maybe you want to buy a franchise...