Neither. In Cyberpunk @ 4K max on a 4090, the difference between the 9800X3D (~$480) and the i3 14100F (~$100) is 1-2%. 74fps vs 72fps
As for the 5090 question, not sure, but there will probably be 0 fps difference between Intel an AMD's top offerings at 4K for a long time.
The German Magazine PC Games Hardware Just tested exactly that. Example: on Baldurs Gate 3 the difference between 9800x3d and 14000k was at 30%. Other Games Had No difference at all or even the Intel winning by some small margin. So depending on the Game, the CPU can be much more important than you think!
You can Look it Up, its all German but the graphs should be easy enough to understand. I'd put a Link in Here but don't know If that's okay...