You may hate to do them, but squats are one of the most effective exercises for the lower body while also working the back and core. Squats create strength and there are a lot of variations. Peter McCall recently wrote an article, Squat Variations, for ACE Fit. He targeted Plie' Squats (which I tend to forget about), jump squats and several others all that are good options. My favorite has always been weighted squats with weights on the shoulder. Whichever method you choose, form is the first thing to learn. I have been known to get our yard stick to make my point about where the knees should be in relation to the toes. I read a lot on line about squat contests as a group of friends decide to challenge each other to a ridiculous reps of squats. The last one I read was 25 squats the first day, 50 the next, adding on until they hit the magic number of 250. Why? I guess because they can. In "Optimal Muscle Strength", Ken Kinakin addresses the issue of muscle growth and strength. You will not find 250 squats in this book. What you will find are weights to increase the work load and a critique of risk and benefit for many variations. For instance, the barbell squat with the feet shoulder-width apart gives equal stress to the muscles while the risk remains very low. With a wide stance the risk factor goes up, but the benefit is still high. Paying attention to your workout is essential to staying injury free. Keep the risk low and the benefit high!
Resources: ACE Fit July 2015 "6 Super Effective Squat Variations You Need To Try" by Peter McCall
"Optimal Muscle Training" by Ken Kinakin