Although NiceHash is usually regarded as a mining service, it's better to say that it's a kind of a platform for selling/buying cloud mining contracts. What is special about NiceHash is that users can opt for both selling and buying the hash power on this platform.
F2pool is a Chinese multicurrency mining pool founded in 2013. Now it has servers located in the USA, Canada, Russia, Singapore, and several other countries. The pool has a big number of supported coins. Currently, it is possible to mine around 40 currencies on F2pool.