If you want the option to have the Windows Classic look (like 9x, 2000, or XP) go with Windows 7. If you don't care about that both Windows 7 and Windows 8 perform about the same and cost the same. Windows 8 does have a few advantages such as faster bootup's, hybrid sleep, improved security and more support life from Microsoft. Though Windows 10 will be a free upgrade to either so the last one really doesn't matter.