Squat - 2 different types

I've been squatting for the past 1.5 years and am still learning how to squat on weekly basis. Here's what I have learned about a year ago and have pretty much focused on this technique.

A lot of the following literature have been pulled from www.exrx.net
except for my comments in bold

During the execution of a barbell squat, the knees and the hips travel in opposite directions away from the foot, or away from the center of gravity. Draw a second line on the knee joint parallel to the line of force. Draw a third line on the hip joint parallel to the previous lines. A relative comparison can be made on the torque forces of the knee and hip. Typically the torque forces are similar for the knee and hip joints on the barbell squat; the knees travel forward the same magnitude as the hips travel backwards. Generally speaking, during a powerlift type squat (bar lower behind the shoulders and a wider stance) the knee does not travel forward as far as a bodybuilding type squat. The hips typically travel back further with the torso bent forward on a powerlift type squat. This emphasizes the stronger hip extensors and adductors and consequently reduces knee extensor involvement. Knee torque is further reduced by a wide stance.

Instructions (http://www.exrx.net/WeightExercises/GluteusMaximus/BBSquat.html)

Preparation

From a rack with barbell upper chest height, position bar low on back of shoulders. Grasp barbell to sides, close to shoulders and position elbows back. Dismount bar from rack and stand with wide stance.

Execution

Descend until thighs are just past parallel to floor. Extend hips and knees until legs are straight. Return and repeat.

Comments

Keep head forward, back straight and feet flat on the floor; equal distribution of weight through forefoot and heel. Knees should point same direction as feet throughout movement.

I've found this to work really well for me. I've got a weak left knee and using this technique puts much less stress on the knees which I believe will allow me to last much longer (in terms of years) while squatting.

The other type of squat is:

Instructions (http://www.exrx.net/WeightExercises/Quadriceps/BBSquat.html)

Preparation

From a rack with barbell upper chest height, position bar high on back of shoulders and grasp barbell to sides. Dismount bar from rack and stand with shoulder width stance.

Execution

Descend until thighs are just past parallel to floor. Extend knees and hips until legs are straight. Return and repeat.

Comments

Keep head forward, back straight and feet flat on the floor; equal distribution of weight throughout forefoot and heel. Knees should point same direction as feet throughout movement.
I've found this to be much more stressful on my knees and I just don't do this type of lift anymore.


Thoughts?