Dorian Yates didn't care for squats and his legs were awesome.
Dorian was still big on smith machine squats and hack squats. Flex, July, 2004 by Dorian Yates:
Q | You don't include standard barbell squats in your thigh routine. Do you not highly rate that exercise?
Dorian Yates | I absolutely rate barbell squats, but I was forced to abandon them in 1986 when I injured my right hip, which required surgery. From then on, I couldn't do freestanding squats without a lot of pain, so I was forced to explore other thigh-mass exercises. Eventually, I devised the following exercise repertoire to circumvent squats while still packing plenty of beef onto my thighs.
LEG EXTENSIONS | I like to start with these as a way to pre-exhaust my quads before jumping into the heavy compound thigh exercises. Extensions are also great for building separation into the front of thighs. Be sure not to jerk or throw the weight up when performing these. A slow controlled movement is what you should strive to achieve. Also, concentrate on the quads as you perform the movement, lifting with them on the way up, holding and squeezing for a second at the top of the movement, and then controlling the weight on the way down. Quick explosive movements--the kind I see so many people do--can easily lead to a knee injury.
LEG PRESSES OR SMITH MACHINE SQUATS | Either of these exercises will serve you well as a squat-replacement exercise. I've found that each relieves much of the hip stress I feel when performing squats, so I'm able to hit my thighs in a way squats simply won't allow. As with extensions, it's important to consider your form. I've seen many guys bounce their upper thighs off their rib cages at the bottom of leg presses. This is an excellent way to crack a rib or damage a knee. Slow and steady wins the race with both of these exercises. Also, don't forget to consciously contract all your thigh muscles through each and every repetition.
HACK SQUATS | I recommend performing these with your toes pointing slightly outward, at around a 30-degree angle to your center line. By doing this, you will more effectively target your inner thighs--an area that many bodybuilders neglect. Focus again on keeping a fluid motion from beginning to end with a pause at the bottom of the movement. That doesn't mean you're resting at the bottom. Stop a few inches before you reach rock bottom and hold for a count of one. This ensures that you've taken all momentum out of the motion and that you're using only thigh power to push that weight back up.