If you are looking for bang for your buck and don’t have a lot of money to throw around, the RX 580 or GTX 1060 will certainly get the job done for some time, considering the GTX 1060 is the most common card amongst steam users right now and they are both comparable performance depending on game and platform (RX 580 does much better in linux than the 1060, but you said you’re using Windows, so the 1060 gets a slight edge with updated drivers).
Find one on sale in the next few weeks and you probably can’t go wrong. They off great performance for the price when you grab them on sale. There are some lower tier ones that also work out pretty well if you don’t expect to run ultra settings.
RX 590 is looking too expensive for the performance at the moment unless you happen to want to buy a couple of the 3 free games they come with (which may be the case, they are pretty major games).