Nicehash is a good direct bitcoins paying mining place.
But if you want to try claymore, try to research it.
Nicehash seems, nice but i guess since bitcoin price is going up, i am mining less amount of equihash, which, i get the same in usd, but it takes longer to get 0.01 to get paid from Nicehash...(now it says october) if i would mine directly Equihash i guess(which is 95% of what i am currently mining, or Lbry if i use Nicehash 2 beta), i might store and choose when to sell currencies, to get better profit, but it would be better to add more cards to mine better.
How many 580's do you plan to start? If you will only going to mine with a certain gpu or only one.
It will totally useless, but you can have some hybrid 1080's, 1080ti depending on your budget.
Well that's mining always risky, more cards higher hash, more profit.