I followed a similar curve, but I saw OS X going to hell in a handbasket after the iPhone was launched and became a huge money maker. Suddenly I couldn't trust OS X updates not to break things anymore, etc etc. I think I went back 100% around 2008. For me, it was a relief to to back to Linux. I know I can trust my Linux system not to change unless I want it to. I know that my Linux apps will 'just work', and I won't have to screw with MacPorts or Fink or whatever the cool kids are using these days.
To the OP: If you know what you want in Linux, I'd say just try the mainline distros (Debian, Fedora, even Ubuntu), see if they meet your needs. If not, maybe Windows. Like other commenters I don't even really hate Windows 7. It's just not well-suited for what I need. I have no experience with Windows 8.