For the latest entry at my "Terps in Big Ten" site, I looked into how the ACC and Big Ten compare in attendance for four sports -- football, men's and women's basketball, and women's volleyball. (Had current statistics been available, I'd have examined wrestling and men's soccer, too.) The overall conclusion is that whether or not the Big Ten's sports are superior to the ACC's (that's certainly the case in football and volleyball, probably is in men's basketball and probably isn't in women's hoops), the conference generally draws better than the ACC, most likely because its members other than Northwestern are huge state universities. Note I also added Rutgers to the Big Ten and Louisville (which draws well in just about everything), Pittsburgh and Syracuse to the ACC.
The entry is at http://terps-in-big-10.livejournal.com/2218.html