I use GOG Oblivion and it runs beautifully on Win10. You don't need any of the mods that "bring it into the 21st century" like the 4GB patch. They do nothing because it's already patched. It is also partly bug-fixed, so what I read about some doors not opening or other silly things - they just never happen to me. I am not running the Unofficial Patch either which is supposed to fix all this - I think the GOG version already has the biggest bugs fixed. This is just my suspicion though.
I don't know about Vortex, but I see a lot of people using it on Nexus, including with GOG Oblivion, so I suppose you should be fine.
Regarding Steam, I have not seen a single mod that was exclusively for Steam or that would not work for Steam. It generally seems to work, although I do see comments here and there that some people need to do special tricks to ge things working properly on Steam. This mostly has to do with names of folders and resource files - Linux is case-sensitive while Windows is mostly not.
OBSE is now on Nexus, it's called xOBSE because I think it's been picked up by other people. The latest version is 22.9. I've had some strange CTDs with it, for me 22.6 seems to work better. But I could never trace those CTDs to anything specific, so it could be something entirely different. Try it and see. If you drop below 22.6, you may find a few of the most recent mods not working properly because they use features introduced after that, mostly events. On the other hand, there is a nasty inventory handling bug in 22.7 and 22.8 which they've been trying to fix (again) in 22.9, don't know if they managed. One of my mods suffers from it, but remarkably not in my game, whichever version of OBSE I use. Like most elusive bugs, you just have to hit it.
But for the most part it is all nice and stable.
This post has been edited by Lena Wolf: Dec 6 2023, 09:35 AM