Joe Wilcox - Mac OS X Lion drove me to Windows 7
Lion is the first Mac operating system that I don't like. Also, I find the hardware options, particularly the all-important display and resolution, to be much better from Windows PC manufacturers than Apple in the same price range.
Others will disagree, but I see in Lion many uncharacteristic user interface and file system changes that smack of Windows Vista. Priorities aren't all in the right place, compared to previous OS X releases, with changes made for Apple's benefit -- such as trying to unify many behaviors with iOS -- and increased complexity where simplicity should be priority.