It's a tough call, but my advice it to just pick one and get started. You simply won't know what works or what doesn't until you start working with your ideas and seeing if they are useful and of value to your customers.

Whatever you choose, make sure you have a passion, drive and enthusiasm for it, or at least a passion and drive to see what works and what doesn't. Also know it's rare that your first business will be a success straight out of the gate.

Give yourself seven to 10 years to learn as much as you can about business and how those principles apply to your own ideas. Then start working, testing, measuring and, most importantly, actually selling your products or services. You'll learn more by doing and making mistakes in the real world of business than you ever will in school or passively watching others.

Remember, business is about what people want to buy, not necessarily what you want to sell.

You should find that sweet spot once you start talking to your potential customers and finding out about their frustrations, constraints, and problems (which you can overcome), as well as their wants, needs and desires (which you can fulfill).