I was in this same dilemma a month ago. I am really familiar with Windows 7, but I've had Windows 8 on my daughter s computer for 9 months and I managed. Also second the Classic Shell.
When I made my new build, I went with Windows 8 and Classic Shell. I've seen a few articles pitting Windows 7 and 8 in games and either they tie or Windows 8 comes out on top by a small margin. Also MicroSoft improved boot times with Windows 8. They really are pretty close once you add Classic Shell and have it boot directly to the desktop.
Overall I'm pretty happy with my choice.