what about cex.io? I've read somewhere on forum that it's good. I've checked out the site and it looks dissent, I didn't register thou.
cex.io offers OVERPRICED and Never-ROI mining contracts. The maintenance fee is 50+% which means they only give you less than half of your profit and take the rest as fees for electricity and datacenter upkeep. Their GHS are way overpriced, 0.002++BTC while other cloud mining contracts offer 1GH at 0.001 with lesser maintenance fees.
At current difficulty and bitcoin price, 1 GH/s hashrate will bring you roughly $0.0045 a day and $0.135 a month (assuming difficulty won't go up).
https://bitcoinwisdom.com/bitcoin/difficultyCex.io is charging you $0.105 per GH/s per month.
https://cex.io/maintenanceSo the maintenance fee is roughly 78%, or in other words, you only get 22% of your mining revenue after the maintenance fee.