What else are you interested in? Peter is best for currency; maybe Reid Hoffman (fatty at LinkedIn) or Dave Morin (Path) or Drew Houston (Dropbox). I do believe China offers the best opportunities for Sinofsky. Problem is after Windows, pretty much everything else in the US is a step down. No-one else is building an OS. Alibaba or Xiaomi in China are. But if he wants to stay in the US, then probably the best options are Facebook (who may one day do their own OS), Palantir (Peter Thiel's), Yahoo (where Marissa is aggressively seeking out senior talent). Then of course, there is Apple and Google - but I assume he doesn't want to be a traitor to Microsoft?