g2a,kinguin,scdkey

anyone used them for windows 10 keys? how did the experience go if so? will be needing one on a desktop im building and don't fancy paying £100 to Microsoft, And is it worth?

The reason I'm asking is it worth is because my friend has the downloadable windows 10 you can get from microsofts website with the watermark saying to 'activate' windows and he says you're paying £100 to remove a watermark and that's it, i'm coming from a mac so I have no experience or know if that's true so if anyone can enlighten me would be appreciated