I don't know how others feel about it here, but I've recently returned to Linux as well and picked Pop!_OS for my gaming PC. The main draw was that you can download a spin with the Nvidia drivers preinstalled, so you can get up and running without any faff. It's also just really nice to use in general.

The caveat to all that is that the Nvidia drivers in the distro's repo are currently a little out of date, although a more up to date release is apparently due "soon" and should be completely tested for compatibility.

Distros like Ubuntu or Mint are great go-tos, but if you're interested in a rolling release, I'd suggest OpenSUSE. That said, there's really no "wrong" distro these days; Steam runs on pretty much anything, and with it comes Proton. NVidia is a bit of a pain in the arse, but I'm running that everywhere here with few problems. The platform has really evolved over the last ten years or so.

Just pick a distro and give it a whirl. Don't like it? Pick another. The only way to learn is to use.

I've been using Linux - off and mostly on - since a year after Linus released his kernel, and so have tried a bunch of flavours. I agree with aperson: you'll receive lots of recommendations, but only you know what you like.

My daily driver is Ubuntu on an i5-7200U (Lenovo ThinkPad), and before that it was Kubuntu. My main PC is an i7-7900K, so similarly long in the tooth as yours, and both CPUs run the Ubuntu flavours just fine.

My personal preference is currently Kubuntu (faster, lighter, and fewer "this is how it is, and you'll be glad for it" decisions). But there are so many others to try. Find a bunch that support Proton and gaming, grab their "live CD" versions, and see which ones work for you.

I'm on Manjaro since like a week ago, and it's been great, barely any tinkering needed, and there are plenty of resources to easily do everything. Kde runs great and it's such a pleasure to use. Also, very easy to install nvidia drivers, just a couple of clicks.

Arch runs great, it's a slight learning curve but you'll figure it out. I'm having personal issues with it lately so I'm trying out nixos today. But arch is usually my go to for older pcs and just in general, especially for how much software is available for it.

Just try Ubuntu - might not be the most nerdy option but after distro hopping I tend to come back to it. Steam is where it's at with gaming. I haven't tried GOG on Linux yet, it requires Wine to run and I ran into an issue (forgotten what it was).

Kubuntu, Linux Mint with Cinnamon, Xubuntu, or maybe ZorinOS.

Especially if you don't want to relearn everything and want things to "Just Work" similar to Windows. If you tried Mint before, it's still really quite good. Maybe even better than you remembered it. I went distrohopping a few months ago only to find out that Mint was still #1 for me, especially with Cinnamon.