I don’t really need to tell you how trustworthy this mining set up is, they actually allow the public to go look at the mining rigs!. (As long as you don’t mind going to Iceland!). So I don’t need to tell you just how great this is. The reason they are in Iceland is that the power cost is very low. (of course if they had a bank of solar panels like me it would be even cheaper, but that would not really work in Iceland!)
I basically use SplititMining and Genesis as they are the most reliable.
Business insider did a piece on them which is worth reading: http://uk.businessinsider.com/photos-iceland-bitcoin-ethereum-mine-genesis-mining-cloud-2016-6
And you can see a video of their mining operation here: https://www.youtube.com/watch?v=7A-mcSOGolM