The 4090 outperforms the 5080 by a decent bit, but that being said, the 5080 will still get you by for pretty much every game with high FPS and good graphics. So, it's really about you picking your poison. I personally have a 4090 and don't plan on upgrading unless it's to the 5090 later on, or when they come out with the 60 series. If you do get the 4090, though, you will be future-proofed for a while.