Any suggestions for a graphics card? ?

Are you going all AMD or are you willing to buy a Nvidia card?

For AMD cards, Within your given pricerange, your options are the RX 5600 XT and the older 8gb RX 580.

The RX 5500XT and the RX 580 are neck and neck in performance. The RX 5500XT might win in terms of lower power consumption, but the 8gb RX 580 has better drivers and usually it's cheaper.

The RX 5700 might be a little bit more expensive than the RX 5600 XT, but the performance gap between these 2 cards is pretty small. 

For Nvidia. Sometimes you can find a 6gb RTX 2060 for $300 but that kind of deal is hard to find. About your only Nvidia option is the GTX 1660 Super or 1660ti. The GTX 1660ti is the slightest bit faster compared to the 1660 Super, so getting whichever is cheaper is better. 

AMD RX 5000 series cards are in lower demand thanks to driver issues. If you have the patience to deal with a potential driver issues then a card like the RX 5600 XT is a good buy. 

The RX 580 or RX 590 are good cards but you'll have to lower the settings a little for 1080p +60fps in some games. With the RX 5600XT, you should be able to run games at max settings at 1080p while getting close to 60fps or beyond. The RX 5600 XT is about 50% to 60% faster than the RX 580.

In most games the 6gb RTX 2060 is a few percent faster than the RX 5600 XT. The 6gb RTX 2060 is about 33% faster than the GTX 1660ti. 

what games are you hoping to play or what do you want to use your pc for?