Like 10-15 years ago I was into linux and tried a bunch of different distros (PCLinuxOS, Mint, CentOS, OpenSuse...) and was quite happy with the, then, limited options of gaming on linux (It was the time Valve released TF2 for linux)
But time passed, I got a new PC and didn't bothered install any linux distro (because I got a small HDD and didn't wanted to split it in partitions for linux)
Back then stuff like Proton did not even exists, so today I'm kind of lost and don't know what flavour I should pick, so here I am asking for advice
A couple of relevant details about the hardware, my PC is a little bit old (i7-7700) I hope that's not an obstacle to enjoy gaming on linux I also have an Nvidia graphic card
Also, while most people just use Steam I also use GOG regularly, if that matters
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.