I have a Pimax 8K and Rift CV1.
The Rift is great to use, fairly simple, very little hassle and I have touch controllers so it's great for room scale gaming, if you're not sure whether VR is for you then it's a great start point.
The Pimax is brilliant, but it is more temperamental. Not for beginners. I just need motion cancellation to be sorted now to get the best out of it, this is on my racing rig and is used exclusively for that purpose. To give Pimax some credit, the software is coming together nicely, and improving all the time. The FOV at medium (1080Ti) is plenty and a noticeable improvement over the Rift, as is the resolution bump (although it's still not crystal clear). Hopefully, I can upgrade my gfx card to get a better experience, I'm expecting this HMD to keep me going for 4-5 years before I need to think about upgrading.
When I got the CV1 it blew my mind coming from pancake gaming, even with triple monitors in racing games. While the Pimax is a big step up from the Rift, it's not the same level of wow! that I got back then.
Sadly, lately my gaming time has been limited by a hectic real life, so I've played hardly any room scale, and not as much racing as I'd like.