Which GPU is a worthwhile upgrade from an RTX 3080 for 1440p?

Out of the listed cards, I’d choose the RX 9070 XT if the extra $80 is manageable. The regular RX 9070 is reasonable, but the XT gives you more performance headroom for high-refresh-rate 1440p gaming and should last longer. I wouldn’t spend $600-plus on a used RTX 4070 Ti when it’s so close to your current RTX 3080 in real-world performance.

Honestly, keeping the RTX 3080 may be the best financial choice. The RX 9070 and RTX 4070 Ti cost a lot for what could amount to only a modest improvement. At 1440p, the 3080 is still capable of running modern games well, especially if you adjust a few demanding settings or use upscaling. I’d wait until you can afford a genuinely substantial upgrade, such as the RX 9070 XT or a used RTX 4080-class card.

A useful way to look at it is in frames per second. If your 3080 currently delivers 50 FPS in a demanding game, a 10–15% upgrade might only raise that to around 55–58 FPS, while a 40–50% upgrade could bring it closer to 70–75 FPS. Unless you specifically need newer features or lower power use, save for the larger performance jump rather than buying the 4070 Ti.

I’d skip the RTX 4070 Ti. Compared with an RTX 3080, it’s only around a 10–15% improvement and the extra VRAM is fairly limited, so it probably won’t feel like a worthwhile upgrade. If you can manage it, the RX 9070 XT is the first option here that should provide a clearly noticeable jump, with roughly 40–50% more performance and 16GB of VRAM.