We do not publish a list of pools we are using. Our main criteria for a good pool are: reliability, fee structure and reject rate. Going forward we will solo-mine a few coins (and pass the fee savings to our users!).
Our internal policy is: “be a good crypto citizen”. This means, that we will at least use two different pools (in some cases we use up to four) for each coin. This is to preserve the decentralized nature of the crypto networks! If we become aware that a pool is getting close to 50% share, we will switch away from it and use a backup instead.