Best defense in college football?

im a buckeye dude an have been impressed with my team so far especially our defense but i want to know your views. before the season started most critics tabbed usc as having the best defense in college football but ive been watching all there games so far an i have to say they dont sure dont look like it. lsu on the other hand looks great especially with their d-line. all i know is that defense wins championships and who ever that is they will take it. i just know for damn sure it aint gonna be louisville.