I've been a fan of weighted step-ups for a long time, although they've never been my primary exercise for a few reasons - mainly powerlifting and ego. I found this cool article that talks about the benefits of step-ups and how they are better for athletes than squats. 

http://www.overspeedtraining.com/legsart.htm

Opinion is the lowest form of intelligence. It requires no accountability, no understanding.
The highest form of knowledge is empathy, for it requires us to suspend our egos and live
in another's world. ~ Bill Bullard