Which would most improve my knees - fat transfer, liposuction, or knee lift? (photos)

I had liposuction done on my entire legs, including above and around the knee. Now my knees sag more. I had fat transfer done to above the knee but it didn't help. Is this because not enough fat was transferred? What will most improve my knees now-more fat transferred, liposuction (with its skin tightening properties), esp to the lower half of the kneecap, or a knee lift to remove excess skin? If a knee lift, where/how long would the scar be? I'd prefer scars over sag.