I use Linux daily at home and at work, but Windows 7 is probably my favorite:

Win7 is an extremely polished, and fast OS. everything just works out of the box and the UI (atleast on MS apps) is intuitive, except for maybe Windows Media.

I have a lot of gripes with OS X, especially the workflow. I find that it's slower to navigate around than Windows, especially if you don't have a trackpad -- OSX heavily relies on its touchpad to be efficient. The keybindings/macros aren't that great either, and are cumbersome and annoying to use. I also have many gripes with Finder. It looks pretty but it's not as efficient as other OS' window managers

This is false. Amazon only recently started using+moving some of its services/fleets to AWS. To this day, a vast majority run on dedicated fleets.

yes, CloudSearch uses/wraps around the search stack developed at A9. The CloudSearch team is also actually at A9.