I've been using Win10 since launch on every system except my main desktop PC (which was built before Win10 came out). All my clients and family and friends are running Win10. Most of these are systems I set up. Why am I not using Win10 on my main personal system? Sure there are things I like about 7 more than 10 (and vice versa), but the main reason is just cuz I've been waiting until I grab a new SSD. Then I'll do a fresh install of the latest version of Win10. Otherwise I've just been dragging my feet. Basically just laziness. I don't do OS upgrades, only fresh installs. My younger bro is also still using Win7 on his main desktop. What he wants to do though is get a gaming laptop and run Win10 on that, and then he can keep his main desktop running only Linux. He hasn't been able to do this because laptop prices are ****ing insane. So much money for such weaker hardware. Rather use the money on a desktop. In any case, despite its issues, Win10 has come a looong way since launch. I certainly don't mind it anywhere near as much as I used to. Every new system I build that isn't designated as a Linux machine gets Win10 thrown on it. Definitely has made it easier to maintain the systems of family and clients.
EDIT: Speaking of DX12 games running on Win7, I played through Gears 5 on Win7. That was not a great experience. Tested using a few different nVidia GPU drivers, all with the same results. The performance was *** on my 1080 Ti and yet the GPU wasn't even close to being fully utilized. I looked up the performance people were getting on 1080 Tis at the time, and my performance wasn't close to matching that. I figured there was some wonkiness going on with me being on Win7. I can't recall performance figures or which driver versions I used, since this was a few months ago or so. Probably got the info written down somewhere. I had bigger problems than the performance though. The game would often crash throughout my whole run through the game, and the game itself was pretty buggy too, with collision detection issues and NPCs wigging out or getting stuck in geometry, all kinds of fun stuff. At some point I'll check out the new CoD Modern Warfare, since that is another DX12 game that will run on Win7. Not sure why devs even bother with DX12 anyways. Just use Vulkan.