Leg extensions
Leg press
Hack squats
This is the perfect quad routine if you dont want to squat.
The benefits of doing heavy squats do not outway the negatives. Back strain, knee strain and a big ass.
If you want a big ass and a bad back then squat your life away. They are also a major cause of hernia's.
This is my quad routine and my quads look pretty damn fine.
If you dont want to squat, dont squat. There are alternatives. Alot of pro bodybuilders dont squat because after years of doing them heavy something had to give.