Ethash for beginning and I will keep in mind cryptonight algorithm. I know that Vega cards is best for cryptonight but amd 570-580 xfx are good too?! Did you mean that cryptonight algorithm use less electricity?
Yes, 570/580's hash 880-1000 h/s on for Cryptonight, and it uses less electric than Ethash. Ethash is still more profitable atm though.