Mikeymikec: There was nothing special about Win7, it was not a bad OS but then I can say that about several Windows and Linux distros.
When I say rehash I meant it followed same layout more or less as previous Windows and offered really nothing special over say Vista SP2 unless you want to count slight speed increase and less UAC nagging, sideways upgrade over Vista SP2 if you ignore the unwarranted FUD about Vista back then.
If Win7 only offered a "slight" speed increase over Vista, I couldn't and wouldn't have offered a lot of customers Windows upgrades to Win7 back in that day; the upgrades weren't cheap and it resulted in a lot of happy customers who could see the very obvious performance difference (mostly in the boot-up and settle-down time). For a lot of machines it made a massive difference. Even on a modern machine with a HDD and is otherwise easily equipped to handle either OS, I bet Win7 would still cold-boot and settle down on it probably a minute quicker than Vista.
Having said that, my wife prefers Vista (the UI really) on her desktop (Sandy Bridge era); if she generally puts it in sleep mode rather than shutting it down, it's as responsive as any modern Win7 PC. That's not really a practical approach for a laptop though, is it.
Win8 and Win10 actually offered something new then just another rehash of desktop PC OS IMHO.
A desktop PC OS has to do a particular job. Its user interface system involves a screen, a keyboard and either a mouse or a touchpad. That's why there's a lot of UI similarities between platforms, including Win8 and Win10, various Linux operating environments/window managers and OS X. Win8x took a beating because its designers ignored the vast majority of their users' needs. The designers of Win10 backpedaled to some extent and came up with something that's a cross between Win7 and Win8x.
I'm failing to see where the extra value is in adopting Win8x or 10 purely from a UI perspective, or what is particularly "new" here.
My point being for a new PC I still think Win10 is a better choice, already stated why ie better security, more features, far longer life span.
Win7 is already over six years old and coming to the last four years of its life, Win10 on the other hand is virtually brand new, software and games companies will be concentrating on Win10 as their main OS for now and the near future.
The "longer life span" and subsequent third party support is the only point here that I think has any significant value; IMHO if I were to build a new machine for a customer and put Win7 on it, it would be incredibly short-sighted. As for extra security, I would suggest that anyone check the vulnerability lists for Win7, 8x and 10. Admittedly I haven't checked them myself yet (I had on a few occasions with Win8x), but I would be very surprised if Win10 has significantly less vulnerabilities than its predecessors, I bet it is receiving just as many patches via Windows Update, and for the same problems as its predecessors, so while I appreciate incremental security improvements, I think it's somewhat blinkered/optimistic to push security as a big reason to adopt Win10.
As for features, I find it somewhat laughable when I look at the steps backwards that the camera photo import system has taken; Win8x doesn't even include an option for deleting camera photos after importing! Win10 thankfully includes that option (which IMO was a total deal breaker), yet it apparently doesn't include the option to specify the folder it should import the photos to. WinXP's photo import system managed this job perfectly well. Vista's and Win7's import system is OK as well.
The two control panels in Windows 10 are also an amusing work-in-progress, but admittedly Microsoft has been fudging the Control Panel overhaul for ten years (since and including Vista), so perhaps expecting them to finally pick a direction was a tad optimistic.