Im using Genesis Mining. I am satisfied with it. Payouts are daily and they are quick to get a hold of should you have any questions or issues.
With that being said, dont expect to make a quick buck. Im sitting at around 7-8 months to get even, nonetheless its still has some potential and you wont have to deal with the excess heat and noise the miners make

They recently ran out of Bitcoin contracts,any idea when there will be new ones ?