Take Econ. I am biased studied econ during my undergrad, but I've heard sports management are looked down upon. Listen to Mark Cuban on Bill Simmons podcast talking down Sports Management. Econ gives you a good base for anything you want to do. Learn the fundamental especially in statistics and econometrics, then you can do a thesis/independent study unit focused on sports in 4th year - studying the market for players (eg. why baseball teams overpay for RBIs etc) or develop a new statistic to measure efficieny in hockey. Econ gives you the tools to analyze the world including sports in different ways. Studying Econ will give you a broader knowledge base when you graduate. Read up on Nate Silver, Daryl Morey, Mark Cuban, Billy Bean -the future of sports is very analytical. I don't know how hard UM Econ is, but you are better taking the path that looks more challenging - sports business is very competitive, you will need to impress potential employers.
Good luck,