The most profitable crypto miner by the hardware only is the contract mining such as CEX.IO (currently 0% fee) and nicehash (0-25%). you can also do single GPU mining with stuff like claymore which now supports ethash . Most AMD GPUs now support Ethash mining as well as Nvidia GPUs that support Pascal / CUDA 8. The highest profit margin comes from dual-gpu miners such as TTJ and NiceHash, especially at lower difficulty levels PoW PoS PoW PoS
2. What is the best pool to join if I want to mine?
Since we recommend cloud hashing providers we will not go into detail about specific pools here but this answer should be enough: https://bitcointalk.org/index.php?topic=504931