when considering ll u have to see more than sitting height. yes sitting height matters a bit but while sitting ppl usually dont compare heights in their minds because noone is sitting straight. i have seen 6'1 guys sitting lower than a 5'10 guy even though they have more of a spine if they wanted to show. (like a million times)
The leg to torso ratio while standing is however important. longer legs to torso can even be a good thing in terms of aesthetics but too long looks off and any lengthening done more than 7-8cm i believe puts in that category, no matter what the starting stats as long as a normal human being.
IMO the most important ratio is the femur to tibia ratio aesthetically, seconded by leg to torso ratio. so due to ll If the knee shifts too low (on men) due to substantial femur lengthening usually (7-8cm) that just looks horrible while walking or sitting and especially while running, no other way to put it. thats not only my opinion but also a friend of mine who has done 3 ll surgeries and then a shortening surgery. according to him and me(purely my own opinion) and many other veterans tibias should almost always be done first.
And if tibias are done too much usually (6-7cm) they kinda still look acceptable with a very high knee.
Also femurs act as a transition from upper extrimity to a lower extremity. If you take the folds of the body, the knees, the hips and neck so femur act like a transition-er. Short Torso, A Godlike femur, and small tibia is like walking death if you care about proportions. The long femurs make both, the torso and the tibs appear smaller as its right in the middle connected to both directly and the lowered knee is just icing on the cake.
Ofcoarse this all matters if you care about proportions. I did my ll a year ago and despite having long tibias for my height and even with a long femur, stil the ratio was about 0.87, i still went with tib lengthening considering all these factors. I did 5cm tibs. Tibias look very very long now but I as a whole stil dont look off. (atleast not if i had done the same amount in femurs). This was all from an aesthetic point of view and not from medical pov as im no expert in that.
leg to torso moire effected in femur coz they do more