I can recommend Dr. Speck here:
http://www.swissklinik.ch/aerzte.php.
He didn't operate on my knee but my shoulder, but the girl next to me had had her knee operated on (Swiss female ski jumper!). He generally operates at the hospital in Einsiedeln, which did not look like much at first glance, but it is very small with very professional and personal attention. Dr. Speck is very competent, operates on various joints regularly and never, ever made me feel rushed, even with all the questions I had. Hope I never have to, of course, but if I ever needed a joint operation, I wouldn't hesitate to go back to him. Oh, it's been almost a year and a half since my shoulder operation and my shoulder is great. My Hausarzt refered me to him on my request, and I requested him based on two separate recommendations from former patients.
About Balgrist: it has a good reputation but I was less than impressed. They put me under a lot of pressure to operate (ankle), which I resisted, and now several years later with lots of self-therapy, I am very glad I chose not to operate.
Good luck whatever you choose. Remember the operation is only the first step: the therapy and exercises afterwards play a huge role in how well you recover.