As for video cards, RX 570/570 4Gb cards gives you the best bang for your buck, you can mine all the popular coins with great efficiency
They are the best on Ethhash (ETH/ETC/others) overall (close on efficiency vs anything else, better on hash/$ vs anything else at recent pricing).
They aren't even CLOSE on efficiency vs current Nvidia cards on equihash (ZEC/ZEN/ZCL/others) though they are in the ballpark on hash/$ at current pricing.
They seem to be better in many cases vs current Nvidia cards on Cryptonight (XMR/others) but get blown away overall by Vega except on hash/$ if you have to pay a TON more than MSRP on Vega cards.
That covers most of the "most popular" coins that are GPU mineable.