please help picking a new GPU

Hello guys, I recently started mining ether(I know I am late to the party) on my gaming pc. it's a ryzen 1700 and a rx 480 8gb drawing 240 watts. I have mined little bit ether and now would like to throw in another card. I have tried and rx480 is not available anymore. Can you please suggest if I should go with rx570 or rx580 8gb(370 AUD). Also keeping in mind that we may not be able to mine ether soon, would I be able to use the 2 GPU's for mining another cryptocurrency? thank you

edit - I realise this is in wrong discussion but I cant find a way to delete the post.