Mike, it's whatever is most profitible for your graphics cards to get the greatest return in YOUR LOCAL CURRENCY.
Have a look on https://whattomine.com/ to help determine this.

Each time you get a mining reward, deciding to invest that in a crypto coin is a separate decision.

For example, if you want more Zcash (ZEC); but it's more profitible to mine Ethereum (ETH), you're best of mining ETH, and selling it for ZEC.

I made a more drawn-out post about this here: https://steemit.com/mining/@rejoys/crypto-mining-as-an-investment

Also note: if your GPU has less than 3GB of RAM, you can't actually mine ETH directly, so you'll be looking at ZEC or some ETH clones, and selling them to buy ETH.