I've yet to hear much positive news about cloud mining so I'd do some serious research before even thinking about investing your btc.
Ponzi's that have already collapsed as predicted:
PBmining.com 1+2+3+4+5+6+7 => 7/7 = Ponzi
Lunaminer.com 1+2+3+4+5+6+7 => 7/7 = Ponzi
coinsoncloud.eu 1+2+3+4+5+6+7 => 7/7 = Ponzi
Cryptomine.io 1+2+3+4+5+6+7 => 7/7 = Ponzi
hashie.co ("gen1") 1+2+3+4+5+6 => 6/7 = Ponzi
bitcoinlabmining.com 1+2+3+4+5+6+7 => 7/7 = Ponzi
ltcgear 1+3+4+5+6 => 5/7 = (very) suspicious
hashprofit.com 1+2+3+4+5 => 5/7 = (very) suspicious
minethatcloud.com 1+2+3+4+5+6+7 => 7/7 = Ponzi
CoIntellect.com 1+2+5+6+7 => 5/7 = (very) suspicious
terabox.me 1+2+3*+4+5+6+7* => 6/7 = Ponzi (pictures are not convincing to me for now, exit strategy involves 60+ days stall tactic)
chabatmining.com 1+2+3+5+6+7 => 6/7 = Ponzi
Ecrypto.co.in 1+2+3+4+6+7 => 6/7 = Ponzi (+ confirmed scam, they are no partners of cex.io)
GenerateBTC.com 1+2+3+4+5+6+7 => 7/7 = Ponz
Likely Ponzi scams that have yet to collapse:
cloudminr.io 1+2+3+4+5+6+7 => 7/7 = Ponzi
cloudmining.website 1+2+3+4+5+6+7 => 7/7 = Ponzi
Skycoinlab.com 1+2+3+4+5+6+7 => 7/7 = Ponzi (+ organized by serial ponzi scammer: ?topic=583177.msg10298730)
btcslice.com 1+2+3+4+5+6+7 => 7/7 = Ponzi (+ pays out in reversible paypal ?)
grmining.com 1+2+3+4+5+6+7 => 7/7 = Ponzi
bitcoinmaker.ch 1+2+3+4+6+7+8 => 7/7 = Ponzi
eobot.com 1+2+3+5+6+7 => 6/7 = Ponzi (+ possible malware/wallet stealing software)
hashwar.co 1+2+3+4+6+7 => 6/7 = Ponzi
bitrush.com 1+2+3+4+6+7 => 6/7 = Ponzi
nexusmining.com 1+2*+3+4+5+7 => 6/7 = Ponzi (Guy from Spondoolies says im wrong, but I cant score what I havent seen and he seems to confirm they have no hardware)
minerslab.com 1+2+3+4+6+7 => 6/7 = Ponzi (+ selling hardware that doesnt exist + using purchased "legendary" account)
bitcoincloudservices 1+2+4+5+6*+7 => 6/7 = Ponzi (+ founded by known scammer https://bitcointalk.org/index.php?topic=860400.msg9638868#msg9638868)
scrypt.cc 1+2+3+4+5+6 => 6/7 = Ponzi (preliminary assessment)
Kryptologika 1+2+3+4+* => */7 = Ponzi -> passthrough of AMhash which is defunct. Currently operating as fractional reserve/ponzi.
hashcoins.com ~1+2+3+4+7 => 5/7 = (very) suspicious (user selectable pool requires fee, dc pictures show no miners, linkedin profile doctored, hardware sales very dubious,..)
Zeushash 1+2+3+4+5 => 5/7 = (very) suspicious
Rest:
Cryptsy MN 1+2+3+4 => 4/7 = Possibly/partially legit ( + no details on fee structure)
cloudmining.sg 1+2+4+7 => 4/7 = Possibly/partially legit
genesis-mining 1+4+7 => 3/7 = Probably legit (risk of fractional reserve mining)
Megamine.com 1+4 => 2/7 = Probably legit
Bit-x.com 1+4 => 2/7 = Probably legit (preliminary assessment, partnership confirmed by Bitfury)
pow88.com 1+2 => 2/7 = Probably legit (preliminary assessment)
KNCcloud 7 => 1/7 = Legit (but as hardware vendor, they broke their promise not to selfmine with more than 5% of customers hashrate )
Hashnest (umisoo) => 0/7 = Legit
Obsolete or suspended:
AMhash => 0/7 = Legit (if you buy directly) / divs momentarily (?) suspended
Cex.io 4 => 1/7 = Legit
Cryptx PETAmine => 0/7 = Legit
GAWminers 1+4+5+~7 => 4/7*= Possibly/partially legit based on criteria set forth. Based on wider context: more suspicious than a nun squatting in a cucumber field
You might want to check out the scam accusations board for more detailed info on cloudmining ponzis.