There always has some debate about which exercise is better, or which one you should teach first, etc. I think that part of the answer has to do with the individual that does the exercise: some are more natural squatters, while others are naturally better at the deadlift.
From the above picture you could derive that you place more “tension” on your knees and hips while squatting and more on the gluteal muscles and muscles of the low back when dead lifting. Obviously the quads are more loaded with the squat.
Some “tension” is good, you need to load the joints and muscles to improve performance. But if you have joint issues, especially knee issues, the squat may not be the exercise of choice for you. You can of course train with light loads to improve your form and do corrective exercises to improve mobility and stability through the lower extremities.
Just as when you have limited hamstring length or increased tone in the posterior chain, the deadlift may not be the best exercise for you. With FMS we would make sure that you clear the ASLR compenent, before loading the deadlift; but again, you can use it unloaded to improve mobility and stability as a corrective exercise.
Gray Cook states in his article that if you look at it from a risk-vs-reward, the deadlift is safer and he recommends: “maintain the squat, train the deadlift”. if you are starting with he deadlift, it is good to reduce the ROM of the exercise. With a kettlebell, you can place them on an elevated surface. If using a barbell, you typically already have an elevated starting point, due to the size of your plates. Kettlebells are the way to go I think, because yo can place them between your feet and really improve your flexibility; or use them one just one side.
The Squat exercise is powerful, but not as powerful as the hip-hinge. By design the hip hinge is mostly a muscular stress, where the squat inherently has to load the lower extremity joints and the low back. There is almost no reason to use a deadlift, as long as it it properly executed.
What about the core?
Contrary to popular belief, the core is trained better by deadlifts and squats than by ab-specific exercises. A study to support this finding was published in the January 2008 issue of the “Journal of Strength and Conditioning Research.”
How about the upper body?
According to “Strength Training Anatomy,” the deadlift uses more muscles than any other single-movement lift. It beats the squat in this regard because during the squat, the bar is passively supported by the shoulders, while during the deadlift, the bar is actively held by the arms.
Source: Balanced Body Series – Dead Lifting, Livestrong
Video: FMS Unplugged