Choosing the right knee exercise depends on your fitness level, overall health, and specific goals. If you're a beginner or have existing knee issues, less strenuous leg exercises like step-ups or half squats might be most suitable. For those looking to build muscle or increase strength, exercises with added resistance like seated knee extensions or using a leg extension machine can be more beneficial. Always consider your personal comfort, the potential risk of injury, and your long-term fitness goals when choosing exercises.