NASCAR. NBA is a close second from the options on the list however overall rank of pro sports would be NFL, NASCAR, MLB, PGA, NBA. The NBA may move up my personal list if Portland is watchable again after the draft.
Let's not argue the merits of what is or is not a sport. It has been done here as recently as three months ago and we all agree to disagree. When you start defining sports you get into areas that exclude many activities some of us consider sport while others do not. We are all quite polished in our debate skills since the summer has brought multiple religious and political threads. Which much like this debate essentially turn into...is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, is not, is so, is not, is so is not, is so, adnauseum