Nvidea: GTX 1050/1050TI/1060/1650
AMD: Radeon RX 470/480/570/580
The gtx 1050 or the rx 470 seem to be the best options. Going higher might not give you a lot more performance in a lot of games, since you will be bottlenecked by the CPU.
If you want to buy a new card, buy a 1650. If you want to buy a 2nd hand card (always try to buy from seller directly/try the card out in a system!) buy a rx 470 for like 70$.