I'd recommend a spotter on the free squats until your form is perfect...form is much more important than the amount of weight.
Do Free squats for full hip, quads, and hams strength.
The Smith allows for better isolation of quads.
There's nothing wrong with relying on the Smith Machine, though. Following is an excerpt from an article entitled "Arnold on the Squat,"
by Arnold Schwarzenegger - 1976
I have reverted to using the vertical sliding Smith machine for my squats. This machine enables me to concentrate on my legs. I can place my feet forward of the vertical line of my body, and I can't fall back, like I would using a barbell. Thus, with my back straight, feet about 10 inches apart, and my knees straight ahead. I do tension squats, going three-quarters of the way down and coming up to a position a quarter of the way form the top. The movement gives my thighs an incredible burn and gets the more lateral muscles. I always do this one before a contest. I burn out as many reps as I can, never completing a movement If you lock out, you give your muscles a chance to rest, and that 's not what you want. you have to torture the muscle with unusual training so that it will respond.
I used to use a lot of weight on the squat. Not anymore. I find now that concentration lends its own form of resistance. By thinking I can direct the effort, I can make every movement count, not only the sets. By doing the sliding squat on the sliding Smith machine, I am able to concentrate using less weight. I direct my attention to what the thighs are doing. I literally think the definition into them. The pleasure of my thought overrides the pain. The positive aspects of cuts and veins and shape spur me on, and the whole thing become a labor of love.
