Don't overthink it. The longer you take to decide, the less time you'll have to enjoy riding.

Just buy a bike, any bike. Ride it around like you have projected for a year or so. During that time make a mental list of what you love about your bike and what you don't like. If you are successful you will be having so much fun that you will reach a point of thinking you deserve a better bike. When you decide to buy your next bike try to maximize your loves and minimize your don't likes.