Ive chosen to go for tibias for 1 reason: aesthetics. Now this is still up for the debate, but I think long femurs look out of proportion. Your knees just hang extremely low, and its noticeable when you run or walk fast. Nowadays everybody is expecting long tibias, the society had taught us that. As for the femurs, you can either go low (like 5cm) and do high bar squats like crazy, or go for quad surgery. There are 2 camps here that preach different strategies: heightmaxxing (get as many of those cms as you can) and proportionmaxxing (get some cms, but keep looking like a human). The decision which is the correct one is up to you, as always.