I had win 10 briefly, but formatted the drive and went back to win 7. My other machines run Linux, and when the day comes that Win 7 isn't working for me, I'll install Linux.
I was much like you, Windows 10 in-place upgrade (back when they were offering it for free) wouldn't take on my PC for some reason, so I stuck with 7 up until this year. I couldn't get a few Windows Updates to take since ~February, spent far too much time troubleshooting across months of my free time, finally decided to do a full, fresh install of 10. Because I had attempted to upgrade back during the free offering, I was still entitled to a free upgrade to 10; MS reps will try to sell you a copy of 10 and tell you it might not work, but I upgraded and used my Win7 key to register without issue. Been on 10 for over a month now, everything works pretty much the same. I have a quad core i7 on a custom-built Asus board with 24gigs of memory, I built it back in 2008. I don't see any benefits to Windows 10, but at least it's done.
One thing that made the process easier was the ability to use Win7's Easy File Transfer/Backup to transfer system files and settings to 10. ETB is not provided with 10, but I read an article on one of the geek sites explaining how you can still use it. Worked great, a few system settings didn't transfer, but that's to be expected with a new OS.