hashflare.io is pretty safe.
But if you look here, you'll notice that right now the best contract have payback period of 813 days. So it's more than two years just to break even. Most of the contracts (all timed ones) never pay back. For example 1-year ethereum mining at hashflare.io will give you net loss of around 30%.
That's kind of a contradiction. You say they are safe, yet you will lose money. I guess you could consider them to be safe because of the transparency -- they let you know ahead of time that you will lose money.
It is odd that people still invest in cloud mining knowing that they will either lose some of their money or all of their money.