While this is not going to a long post, we mined with Antminer S1s to BTCGuild for about a month and received around .0215BTC per day per Antminer. With Cex.io, we are generating about 0.026BTC per day. While it is not that much of an increase, the multiple payout addresses and easy in-site trading with CEX.IO has to put it above BTCGuild in our opinion!