For gaming only, no mining.
He also asking, would in the feasible future 6700XT will offer better ray tracing performance after games will optimize for AMD's ray tracing hardware?
Thank you ahead,
If your friend wants consistent driver quality, I would recommend the RTX 3070. I am writing this from personal experience, even though I am a fan of radeon, there comes a lot of frustration with it, since often with new drivers when AMD optimizes for looking nice on new gaming performance adverts, AMD also causes worse performance in older titles or even completely break some feature for some series of cards and half of the time without ever fixing them.
If he/she is looking to have nicer input response; especially for E-sports gaming; I would likely recommend the Radeon, not necessarily because it performs better, but a lot of times feels more snappy (even without the anti-lag/chill features). Furthermore, game graphics looks very slightly different sometimes; for example, for me Radeon looks a little more bright/crisp, whereas nvidia sometimes looks slightly more dark at same colour settings.
As far as I know the 6000 series supports Ray Tracing through DXR, so games that use DX12 DXR will be able to be optimized for Radeon, but that would probably depend on consensus between the game developers and AMD/Nvidia graphics developers. It is 50/50 but usually more like 40/60 with AMD being the 40 if that makes sense.
EDIT: Forgot to mention, AMD has really nice recording tools if he/she is looking to do live-streaming.