AMD, easily. Its literally plug and play. You can even pick some second hand options for cheap that are still solid for gaming such as the vega 56/64 and the RX 5700XT (which is I use). Intel isn’t bad so long as you’re not playing the newest stuff, my Arc a750 is solid in games like Fallout 4 and Elden Ring. Starfield is complete mess on it. Another thing with Intel is you’ll need a distro with a 6+ kernel to get the most out of it.

AMD is better on Linux most of the time. Running a AMD card day one is not hassle free.

That being said if you pick a up to date distro all 7000 and 6000 series should work fine now. They are already in the kernel and mesa for a while. You may want to update you kernel and mesa sometimes to get better performance and stability.

But in my experience nvidia is fine on Linux. (I only used older cards gtx 970 and a rtx 2060) especially when you have just one monitor or all monitors on the same refresh rate. It’s not on par with windows but will work with the Nvidia drivers.

So I would say if you a simple setup Nvidia is fine and AMD is better. It all depends on the best deal you can get. If ray tracing is not that important AMD is new the best value. If you more on a budget second AMD Rx 5700 XT are pretty cheap here and there are some good deals on Nvidia 30 series cards.

As far I have read intel cards can be a pain on Linux. So I would not recommend it for now.

AMD is generally better

If I were buying a card right now I’d get either the 6700XT or the 6800XT because they’re both at crazy good value for the money right now, especially if you can get one used or refurbished from a reputable seller with a return policy.

This sums up my feelings on Nvidia.