We recommend the AMD RX 580 Series or the NVIDIA GTX 1660 Series for a good compromise of details and fps with the most recent video games. Not above a RTX 3060 Ti or RTX 3070 Ti if you are using only a single monitor with full HD (1080p or 2K) resolution. Spending more money is only logical when using higher resolutions or multi monitor configurations.
Top tier VGAs are AMD 7900 XTX and NVIDIA RTX 4090, delivering ultra-high frame rates and serious levels of 4K resolution gaming. Software technologies such as NVIDIA DLSS and AMD FidelityFX Super Resolution allow increasing the performance of the video card at high resolutions through upscaling algorithms, obtaining big improvements in terms of FPS and at the expense of a minimum image quality loss. While DLSS is for the exclusive use of NVIDIA RTX video cards, the AMD counterpart is supported by more cards from both manufacturers.
Once you have picked your GPU, you have to decide the specific model. Some models are equal to the producer reference board (AMD or NVIDIA) and in that case there isn't really a good reason to choose one over the other. Sometimes manufacturers decide to personalize card layout, components, heat sinks and running frequencies. When is a specific manufacturer’s card worth it? That really depends. It is not convenient to spend more to pick only slightly overclocked models, or in some cases where the custom heatsink does not bring any significant advantage compared to the reference one.
Should I buy 2 slower cards instead of a single more powerful one at the same price? The answer is no. Within the current market, it is always more convenient to pick a single card. Also, SLI/Crossfire support is going to die soon.