I have been using the Pimax 8KX since it launched 2019/2020. I also own the Oculus Quest 3, and I used to have the Go.
To me, the FOV was and is still the gamechanger for VR porn and VR gaming. Gaming can sometimes be tough if it's a very active and mobile gaming experience, but for everything else, the FOV makes me feel more immersed.
But especially for porn... I love sensory overload, and I love multi-girl scenes. So when I use smaller FOVs, I can't really see all the girls at once. With the 8KX, it really allows me to fully see all the action on the sides, above me, below me (girls kissing my cheeks, licking my nipples, riding me on top, etc).
I use my Quest 3 only for travel and for Passthrough. It can be a fun experience, but I don't get lost in the moment as often. I also don't like having to find the controllers with the headset on. With mouse and keyboard and PC headsets, I think it's just more convenient for me to be in front of my computer, easy access to my desk/mouse, etc.
I also download videos to watch, so of course, having the PC makes sense. If you just prefer to stream and be flexible with your environment, or mimic the positions of what you see in VR (standing POV, laying down POV, etc), then yeah, the Quest is great.
As far as visual quality, I will definitely say the Quest 3 color is quite good and in some ways has a stronger sense of depth than the Pimax 8KX. But I think that may have something to do with my particular IPD. The Pimax lens can't physically get as close together because of how big the two panels are, and I have a relatively more narrow IPD than the average. I have some horizontal correction on my Pimax software that accommodates that, so I don't have any eye strain at least. As far as resolution though, of course Pimax has higher resolution and so I can definitely see more detail in the girl's skin, etc. This of course is a big nice-to-have too, but not as much as a game-changer to me as the FOV, because 8k porn videos themselves often lack clarity, or have too much compression, etc. I think the resolution aspect is still kind of soft-locked based on the VR cameras / tech being used, more so than the headsets we use.
Anyways hope that was somewhat helpful. If the Pimax 12KX ever comes out, I will get it but at this point I don't think it will lol.