Hi Klaus,
I've been using the HTC Vive for a while now (11+ months). I have never felt sick once in VR. I do get sick if I watch someone else play driving games on a monitor though. If you plan to do any "room-scale" VR, then an HTC Vive is for you. If you only ever sit while gaming in VR, like driving or flying etc. then the Oculus Rift will work. The Vive is better, but to each their own. It is also a little more expensive.
I've just upgraded my computer to the AM4/DDR4 platform, and put a GTX 1080Ti graphics card on it. It is VR heaven. The play is silky smooth, and the images are clear and steady. I have good resolution in my headset, and readability is acceptable/good. It use to be worse, but times change and improvements come along. Dex also mentioned an interest in VR. I wonder how he is doing with his?
Oh, the helicopters!!! Flying a helicopter in VR is like no other experience. Your situational awareness is greatly improved. It makes it much easier to land and maneuver in close proximity to obstacles.