You hate having to load and unload the machine with plates because your back hurts?!
I bet it does.
Leg presses, when done "properly", are horrific on the low back. Sure, some get great results from generally shallow leg pressing and doing tonnes of volume, but for those who are not set-up in this way and/or not on drugs, full squats cannot be beaten.
Big wheels developed through leg presses often look unfinished. Like they're not really real-world functional.
Avoid leg extensions for anything but perhaps light warm-up sets. Heavy extensions will destroy the knees faster than ANYTHING. Largely useless exercise unless you're someone who has just woken from a two-year coma. Think about it: when in real life does a human flex his knee without any hip flexion? That's right, never.
The freebar full squat, done well, is one of the very safest movements one can do in a weight-training gym.
However, many are simply too weak of will and body to wiggle their asses under that barbell and bend the knees sufficiently.
I have been squatting ass-to-grass for 26 years and have never had a knee issue. Last weekend I raw (and drug-free) squatted an easy 650 in my meet.
