Should I upgrade to 10, or keep 7?

I'm staying clear of the free upgrade, not sure what will happen to retail upgrades after the 29th. Will it be transferable and obtain the rights of the original base licence? Some say yes, others say the upgrade is tied to the hardware it's activated on. Nobody knows 100% for sure, so I haven't bothered. There's nothing in 10 that makes me go wow anyway.

If I change my mind in future and it appeals to me more, I'll just buy a retail version, at least then I know I can do what I want with it.

Tried a recent anniversary update build in a VM and it's definitely an improvement over the November update, but still hasn't made me want to upgrade yet. I still have a few years left on 7 and I'm happy with it.

As others have said, do a full system image using Macrium and try it out and see what you think. Different strokes for different folks. You might love it and have nothing to lose.

Oh yes, I would definitely make a back up Image of my current installations..

Also, IF, i were to do a clean/fresh install of 10, it would likely be on my main rig, the 4690K as that has all the most recent hardware in it... as well as a NVMe SSD to take full advantage of what 10 has to offer for SSD's.

Catch being though that, thats the rig with all my games, some of which are pretty heavily modded (Skyrim, Fallout4, etc) ... one of them has over 200+ mods installed, and it would just be a huge nightmare, to have to go and redo all that after a fresh install of Windows. My only option would be to make back up copies of the various game installation folders and mod manager folders... then install those fresh then copy/paste the backups over the new installs...

In all, I could be looking at, at least 2 nights worth in work for just that one.

I don't really have much experience with upgrades, I've never bought an upgrade licence. Every Windows version I've owned, I've only ever bought Retail licences and clean installed. Not as much of a chore these days as it was in the Windows 95 days!

I've seen some people say the 10 upgrade went very smoothly, but for others it's been a nightmare.

I will have to repeat what others have said. Absolutely make an image backup first. Actually make two image backups using two different pieces of image software. Believe me, having worked in computer support for twenty something years and after being burnt in the past because the latest version of a particular image backup software that used to work, now refused to restore, I learned my lesson. Personally I use Clonezilla and Window's own image backup program (Not sure, but that may only be available with the Professional version of Windows). Clonezilla is great because the operating system being backed up is never loaded, so no conflicts with open files, etc. I use it for all my Windows and Linux computers, both desktops and laptops, many with multiple hard drives or using SD cards or other types of solid state memory.

Case in point. I waited until last month before going ahead with the upgrade, thinking that things might have stabilized, but my Win 7 to Win 10 desktop upgrade was a disaster, with different Blue Screens of Death during each boot. Clonezilla saved the day. I reverted back to Windows 7, then did a File (Not an Image backup) to an external hard drive, made a list of all my programs and their settings, and did a clean install. I usually do clean installs anyways; just got lazy this time. My computer is now blazingly fast, but I am sure it is not because of Windows 10, but because the clean install removed a ton of old stuff and cleaned up the operating system; I had been running Windows 7 since it was first introduced and installed and / or removed a ton of programs in that time.

Now for the question, should I upgrade. I guess that is a personal decision. For me the number one reason to do so was be running the latest actively security patched and developed version of the operating system. You know damn well they will be putting more time and effort in supporting the current OS. The fact that it was free was an added bonus. As far as Win 10 itself, it is just like WIn 7 with some cosmetic enhancements. Does the same things as Win 7 did, just took me a little time finding where they moved a couple things in the menu system. All my programs still work. I know you can't turn every privacy stealing thing off, but I was able to turn most of the privacy related data collection items. No different than my Android apps monetizing my web searching. I am on Linux most of the time anyway, so it is a moot point.

I appreciate all the advice everyone has given me.

I have one more question though.

My primary rig has a Samsung 950 Pro m.2 Series NVMe SSD which is currently my primary boot drive with Windows 7 Ultimate on it.

However Win7 was not fresh installed on it. Instead it was imaged over from an older HDD installation... so the Samsung is not properly configured with GPT.

Could I partition off say 100GB of space as a seperate partition. Reformat that and redo it all properly and do a fresh and clean installation of Windows 10 onto that?

Thus then I could keep my Windows 7 temporarily on its seperate Partition... Spend some time learning about Windows 10, copy over things like my Steam Folder, etc...

Then when ready, wipe out the 7 Partition and redo it and merge it back into the 10 Partition?