I'm considering upgrading my PC's graphics card, but I'm not very familiar with current GPU options. The system has a fairly capable Intel i5 and 16GB of RAM, while the graphics card is an older Radeon RX 580. It still handles older, less demanding games such as Total War: Shogun 2 and Tropico well, but newer games and demos haven't looked especially good. I'd like to find a sensible performance upgrade without overspending. My ideal budget is around £300, although I may be willing to pay more if the value is worthwhile. Some used cards seem almost as expensive as new ones, so I'd also appreciate advice on whether buying new or second-hand makes more sense.
4 Answers
For a new card, an RX 9060 XT 8GB could be a sensible choice if you can find one below £300. It should provide a substantial upgrade over the RX 580 without going too far beyond your budget.
A used RTX 3060 Ti for roughly £200 could be a strong value option. It’s considerably faster than the RX 580—around two and a half times as fast in many workloads. New cards with similar performance include the Radeon RX 7600 and RTX 5050, which tend to cost close to £300. The main drawback is that all of these options have 8GB of VRAM, just like your current card.
The RTX 3060 Ti looks like a pretty good option, especially at that used price.
A used XFX Swift RX 9060 XT may also be worth considering. It has relatively low power consumption, a compact design, and good performance. Whether it’s worthwhile depends on the used price—if it’s close to the cost of a new card, the new one may offer better peace of mind and warranty coverage.
It does seem a little expensive second-hand, so I’d want a meaningful saving before choosing it over a new card.
Before choosing a card, check the exact model and generation of your i5. Some older or lower-end i5 processors could limit the performance of a newer GPU, particularly in strategy games where the CPU can matter as much as the graphics card. If the processor is reasonably recent and the power supply is suitable, the cards mentioned above should be sensible upgrades.

I found some listings, but a few are still showing as pre-orders without a clear availability date.