Windows 8
So far, so good. I also tested the beta versions of Vista and Windows 7 and this is by far the smoothest and easiest transition. I had a smooth, glitch-free download and I really like the added security of "Bitlocker" which I didn't have in Windows 7. So far the only driver issue I had was with my HP printer, which was easily resolved by installing the driver manually with the "advanced printer setup" under "Devices and Printers."
Thanks for the "Cheat Sheet!" ~ @rcl4rk