Primary vs. Solitary

Let's say there was a product out there that didn't do everything. It made some compromises. It didn't have all the features to make it the only product of it's kind in your life. Does that mean it can't be the primary product that you used most of the time? Of course not. If it allowed you to do 80% of the stuff you do, you can go and spend 80% of your time on it. That would make it your primary ____ if not solitary ____.