It's personal preference, there hasn't been any proof of better gaming on Windows 8. Go with the one that you like. Once you get used to Windows 8 user interface, it begins to feel easier and slicker than Windows 7, but that's just me.
Window 8 has too many improvements over Window 7 to consider Window 7 for a new build.
Sure, it was rude of Microsoft to make a desktop user boot into a tablet UI but I do understand the need to do that for marketing reasons. They are attempting to unify their product bases (Windows desktop, Windows phone, and Xbox) and gain entry into the ARM market with surface.
- If you are a desktop user, just schedule a task to run at logon to kick you into the desktop, turn off your active tiles to reduce network noise and continue as you have been with Windows 7
- Windows key + x gives me access to a lot of the items I need