I bought a Windows 7 Professional Product Key for only $2.53. Now that they're dirt cheap, as Win 7 support is good for another 2 years and the free Windows 10 upgrade period is over, I said why not to fully complete my upgrade from Vista finally. I didn't trust these key sellers, I didn't think Windows Activation was gonna work, but it did so purty cool to get that out of the way!
I think Windows 7 was the cleanest OS Microsoft produced, all the best of XP & Vista and less of the worst. Windows 8.1 moved the OS into the tablet craze of interface design, same with Windows 10 but with more spying like Google's Android, pretty much moving it to that model.
Well, I dunno how long I should stick with it, but I'll see how it goes in the next 2 years for my home PC. All my tablets are Windows 10 now (up'ed free from 8.1), and my phones are Android, so I have them all at my disposal to continue learning from on occasion.
https://s5.postimg.cc/5r73kzgzr/Screenshot_2018-04-10-19-45-19.pngListing was quickly deleted after seller finished off his batch, but you just eBay search "windows 7 key" to find others.