If they are IN the snow, it tends not to be a knee issue...ON the snow, I see your concern.I enjoy skis with many different personalities, so for me, there is definitively no *best* ski.
But there are a few characteristics that every ski I own must have. They must never be over 100mm in width (I have creaky knees), and they must be forgiving enough to ski all day. If the snow conditions are unexpected, they need to allow me and my average skills to still ski anywhere I want.
I also (unconsciously) have shied away from the most popular *it* ski.....I enjoy skiing skis that one doesn’t see all over the hill.
Ha, now I’m wondering whether there’s a deeper psychological reason for this.....do my ski choices reflect some of my desires to be be a nonconformist and embrace the quirkier things in life, while still valuing loyalty and dependability?